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.
This guy is right on! You should learn new skills that are critical to your success instead of focusing on your business. Just making a website is easy, making one that is easy for your users to navigate, captures your users' interactions, feed that back to a CRM so you can act on it and setting up automation to handle each one properly so you don't lose the customer is not. (And do not forget, the design of your site is critical to the effectiveness of Google and Microsoft Ads. Without them, no one will ever see your new, beautiful site.)
The ADA has been criticized on the grounds that it decreases the employment rate for people with disabilities[48] and raises the cost of doing business for employers, in large part due to the additional legal risks, which employers avoid by quietly avoiding hiring people with disabilities. Some researchers believe that the law has been ineffectual.[49] Between 1991 (after the enactment of the ADA) and 1995, the employment rate of men with disabilities dropped by 7.8% regardless of age, educational level, or type of disability, with the most affected being young, less-educated and mentally disabled men.[50] Despite the many criticisms, a causal link between the ADA and declining disabled employment over much of the 1990s has not been definitively identified.[51]

Error prevention on important forms (3.3.4): For pages that create legal commitments or financial transactions or any other important data submissions, one of the following is true: 1) submissions are reversible, 2) the user has an opportunity to correct errors, and 3) confirmation is available that allows an opportunity to review and correct before submission.
State and local governments will often post documents on their websites using Portable Document Format (PDF). But PDF documents, or those in other image based formats, are often not accessible to blind people who use screen readers and people with low vision who use text enlargement programs or different color and font settings to read computer displays.
The ADA itself holds different organizations to more/less stringent standards based on a host of factors, government funding being a major one. Government agencies themselves are usually held to the most severe standards. That said, while ADA has adopted WCAG as the defacto standard, from what I’ve seen it appears they’re going with AA compliance as the most reliable one. That said, we’ve done work with some organizations who’ve chosen to comply with AAA in an effort to be as buttoned up as possible from an accessibility and experiential perspective. We’ve also worked with some who have tighter budgers and aim for level A compliance and have a more “react and repair” mindset when they discover anything in their site that is giving someone hardship from an accessibilirt standpoint.
This is an article that most other website developers probably don’t want you to read. The reason is that most other web designers basically like to think of themselves as all-powerful wizards with magical powers. And they use complex technical jargon and terminology to intimidate and mystify their clients into thinking that what they do is more complex than it is.

I own a medical practice in California with 5 employees. Since I have under 15 employees am I exempt from needing to have my website comply with the ADA? I know that my physical practice is exempt from ADA policies regarding employment (under 15) but I don’t know if that extends to websites. My website is not an important part of my practice and I don’t really want to sink any funds into it if I don’t need to.