...the full and equal enjoyment of the goods, services, facilities, or accommodations of any place of "public accommodation" by any person who owns, leases, or operates a place of public accommodation. Public accommodations include most places of lodging (such as inns and hotels), recreation, transportation, education, and dining, along with stores, care providers, and places of public displays.
A. The ADA permits an employer to refuse to hire an individual if she poses a direct threat to the health or safety of herself or others. A direct threat means a significant risk of substantial harm. The determination that there is a direct threat must be based on objective, factual evidence regarding an individual's present ability to perform essential functions of a job. An employer cannot refuse to hire you because of a slightly increased risk or because of fears that there might be a significant risk sometime in the future. The employer must also consider whether a risk can be eliminated or reduced to an acceptable level with a reasonable accommodation.

Title II of the ADA prohibits discrimination against qualified individuals with disabilities in all programs, activities, and services of public entities. It applies to all state and local governments, their departments and agencies, and any other instrumentalities or special purpose districts of state or local governments. It clarifies the requirements of section 504 of the Rehabilitation Act of 1973, as amended, for public transportation systems that receive federal financial assistance, and extends coverage to all public entities that provide public transportation, whether or not they receive federal financial assistance. It establishes detailed standards for the operation of public transit systems, including commuter and intercity rail (e.g., AMTRAK).
The words in the tag should be more than a description. They should provide a text equivalent of the image. In other words, the tag should include the same meaningful information that other users obtain by looking at the image. In the example of the mayor’s picture, adding an “alt” tag with the words “Photograph of Mayor Jane Smith” provides a meaningful description.
Under 2010 revisions of Department of Justice regulations, newly constructed or altered swimming pools, wading pools, and spas must have an accessible means of entrance and exit to pools for disabled people. However, the requirement is conditioned on whether providing access through a fixed lift is "readily achievable". Other requirements exist, based on pool size, include providing a certain number of accessible means of entry and exit, which are outlined in Section 242 of the standards. However, businesses are free to consider the differences in the application of the rules depending on whether the pool is new or altered, or whether the swimming pool was in existence before the effective date of the new rule. Full compliance may not be required for existing facilities; Section 242 and 1009 of the 2010 Standards outline such exceptions.[21]
ADA disabilities include both mental and physical medical conditions. A condition does not need to be severe or permanent to be a disability.[6] Equal Employment Opportunity Commission regulations provide a list of conditions that should easily be concluded to be disabilities: deafness, blindness, an intellectual disability (formerly termed mental retardation), partially or completely missing limbs or mobility impairments requiring the use of a wheelchair, autism, cancer, cerebral palsy, diabetes, epilepsy, Human Immunodeficiency Virus (HIV) infection, multiple sclerosis, muscular dystrophy, major depressive disorder, bipolar disorder, post-traumatic stress disorder, obsessive compulsive disorder, and schizophrenia.[7] Other mental or physical health conditions also may be disabilities, depending on what the individual's symptoms would be in the absence of "mitigating measures" (medication, therapy, assistive devices, or other means of restoring function), during an "active episode" of the condition (if the condition is episodic).[7]
This title outlines the administrative processes to be followed, including requirements for self-evaluation and planning; requirements for making reasonable modifications to policies, practices, and procedures where necessary to avoid discrimination; architectural barriers to be identified; and the need for effective communication with people with hearing, vision and speech disabilities. This title is regulated and enforced by the U.S. Department of Justice.

UPDATE: Since writing this post in August 2017, several important changes have taken place in the laws regarding ADA compliance for websites. On December 26, 2017, the Department of Justice announced that they have withdrawn the Obama-era Advance Notice of Proposed Rulemaking mentioned in this article which intended to require ADA website compliance. The DOJ’s withdrawal announcement stated, “The Department will continue to assess whether specific technical standards are necessary and appropriate to assist covered entities with complying with the ADA.”

A. No. The ADA does not require that an employer hire an applicant with a disability over other applicants because the person has a disability. The ADA only prohibits discrimination on the basis of disability. It makes it unlawful to refuse to hire a qualified applicant with a disability because he is disabled or because a reasonable accommodation is required to make it possible for this person to perform essential job functions.
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.

The Americans with Disabilities Act of 1990 or ADA (42 U.S.C. § 12101) is a civil rights law that prohibits discrimination based on disability. It affords similar protections against discrimination to Americans with disabilities as the Civil Rights Act of 1964,[1] which made discrimination based on race, religion, sex, national origin, and other characteristics illegal. In addition, unlike the Civil Rights Act, the ADA also requires covered employers to provide reasonable accommodations to employees with disabilities, and imposes accessibility requirements on public accommodations.[2]

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/)