The type of operating system and hosting doesn’t matter much for design, but the platform is a factor. For instance, if you need a WordPress theme, the designer must work with WordPress themes and customize them in a way that a developer can feasibly code in CSS or JavaScript on the front end. If you use another CMS, the developer must work with those elements. Most designers specialize in specific platforms, so review their portfolios and experience for specific platforms before you invite them to bid on your project.
The next factor is language. Although web design doesn’t require someone who speaks the same language, it’s important that your designer understands your requirements. This can be more difficult if you don’t speak the same language fluently. You can interview a freelancer to explain your requirements and get a feel for their understanding of the project before you begin.
Another important consideration is that the ADA does not allow businesses to simply provide an alternative such as a phone number. Lastly, include accessibility issues as part of your website and mobile strategy. When new technologies are implemented or pages added, part of the process should include the implications for persons with disabilities. 

Aloha Tatiana! I wish your questions had straightforward easy answers – and if you are government funded it kind of is. (See here: https://www.ada.gov/websites2_prnt.pdf) if you are not government funded, this is something that is currently being debated in the legal system. That being said, the WCAG 2.0 guidelines are a good set of guidelines to help protect yourself if you feel you should. (You can see more on WCAG here: https://www.yokoco.com/find-out-how-to-make-your-website-compliant/)


Prohibited discrimination may include, among other things, firing or refusing to hire someone based on a real or perceived disability, segregation, and harassment based on a disability. Covered entities are also required to provide reasonable accommodations to job applicants and employees with disabilities.[16] A reasonable accommodation is a change in the way things are typically done that the person needs because of a disability, and can include, among other things, special equipment that allows the person to perform the job, scheduling changes, and changes to the way work assignments are chosen or communicated.[17] An employer is not required to provide an accommodation that would involve undue hardship (significant difficulty or expense), and the individual who receives the accommodation must still perform the essential functions of the job and meet the normal performance requirements. An employee or applicant who currently engages in the illegal use of drugs is not considered qualified when a covered entity takes adverse action based on such use.[18]
Title II prohibits disability discrimination by all public entities at the local level, e.g., school district, municipal, city, or county, and at state level. Public entities must comply with Title II regulations by the U.S. Department of Justice. These regulations cover access to all programs and services offered by the entity. Access includes physical access described in the ADA Standards for Accessible Design and programmatic access that might be obstructed by discriminatory policies or procedures of the entity.
Since March 15, 2012, ADA compliance with the 2010 Standards will be required for new construction and alterations. In the period between September 15, 2010 and March 15, 2012, covered entities may choose between the 1991 Standards ADA Compliance (without the elevator exemption for Title II facilities), the Uniform Federal Accessibility Standards (Title II facilities only), and the 2010 Standards ADA Compliance.
The idea of federal legislation enhancing and extending civil rights legislation to millions of Americans with disabilities gained bipartisan support in late 1988 and early 1989. In early 1989 both Congress and the newly-inaugurated Bush White House worked separately, then jointly, to write legislation capable of expanding civil rights without imposing undue harm or costs on those already in compliance with existing rules and laws.[27]
The U.S. Department of Health and Human Services (HHS) also enforces Title II of the ADA relating to access to programs, services and activities receiving HHS federal financial assistance. This includes ensuring that people who are deaf or hard-of-hearing have access to sign language interpreters and other auxiliary aids in hospitals and clinics when needed for effective communication.
Predictable: Websites should operate in ways that are familiar and predictable. When a new page element is in focus, the website should not initiate a change of context such as opening a new window or going to a new page. In addition, the website should warn of user-initiated changes of context ahead of time, for instance through the use of a submit button. Navigation and labeling should remain consistent between different pages.
An employer cannot require you to take a medical examination before you are offered a job. Following a job offer, an employer can condition the offer on your passing a required medical examination, but only if all entering employees for that job category have to take the examination. However, an employer cannot reject you because of information about your disability revealed by the medical examination, unless the reasons for rejection are job-related and necessary for the conduct of the employer's business. The employer cannot refuse to hire you because of your disability if you can perform the essential functions of the job with an accommodation.
The Department has assembled an official online version of the 2010 Standards to bring together the information in one easy-to-access location.  It provides the scoping and technical requirements for new construction and alterations resulting from the adoption of revised 2010 Standards in the final rules for Title II (28 CFR part 35) and Title III (28 CFR part 36).
The trick to finding top web designers is to understand what you’re trying to build. There’s a big difference between designing a landing page meant to be the receiving end of a sales funnel and building an enterprise site that will serve corporate clients. The web designer is responsible for translating your unique brand identity into the visual elements that make up a website. The cost of your project will depend largely on your scope of work and the specific skills needed to bring your project to life.

This is particularly important when working for a government agency or government contractor, as these organizations must follow web accessibility guidelines under Section 508 of the Workforce Rehabilitation Act of 1973. Although ADA and Section 508 compliance are different, the published checklist for Section 508 compliance offers insight into ways to make websites accessible for people with disabilities, and thereby work toward ADA compliance.


^ Esshaki, Tiffany (July 21, 2015). "Remembering the 'Capitol Crawl'". C&G News. Retrieved January 15, 2016. The event, known as the "Capitol Crawl", was an image that legislators couldn't ignore, Bauer said. She had fought since the 1960s to legally protect the rights of people with disabilities, and with that heroic display, she said, lawmakers simply couldn't go back to their constituents without action.
Title II applies to public transportation provided by public entities through regulations by the U.S. Department of Transportation. It includes the National Railroad Passenger Corporation (Amtrak), along with all other commuter authorities. This section requires the provision of paratransit services by public entities that provide fixed-route services. ADA also sets minimum requirements for space layout in order to facilitate wheelchair securement on public transport.[20]
Another important consideration is that the ADA does not allow businesses to simply provide an alternative such as a phone number. Lastly, include accessibility issues as part of your website and mobile strategy. When new technologies are implemented or pages added, part of the process should include the implications for persons with disabilities. 
As I mentioned above, under each WCAG 2.1 principle is a list of guidelines, and under each guideline are compliance standards, with techniques and failure examples at each level. Some guidelines include only Level A items; others include items for multiple levels of conformance, building from A to AAA. At each stage, you can easily see what more you would need to do to reach Level AA or AAA. In this way, many websites include elements at multiple levels of accessibility.
This was a case filed before The United States District Court for the Eastern District of Michigan Southern Division on behalf of the Michigan Paralyzed Veterans of America against University of Michigan – Michigan Stadium claiming that Michigan Stadium violated the Americans with Disabilities Act in its $226-million renovation by failing to add enough seats for disabled fans or accommodate the needs for disabled restrooms, concessions and parking. Additionally, the distribution of the accessible seating was at issue, with nearly all the seats being provided in the end-zone areas. The U.S. Department of Justice assisted in the suit filed by attorney Richard Bernstein of The Law Offices of Sam Bernstein in Farmington Hills, Michigan, which was settled in March 2008.[66] The settlement required the stadium to add 329 wheelchair seats throughout the stadium by 2010, and an additional 135 accessible seats in clubhouses to go along with the existing 88 wheelchair seats. This case was significant because it set a precedent for the uniform distribution of accessible seating and gave the DOJ the opportunity to clarify previously unclear rules.[67] The agreement now is a blueprint for all stadiums and other public facilities regarding accessibility.[68]
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