I\'m having trouble finding a clear answer as to whether as site can pass for at least WCAG 2.0 level A if it uses AJAX in some way.
For example from WCAG2.0 state
To your first question, and keeping up the use of WebAIM as a great resource, it doesn't look like sites have to work without Javascript anymore, at least according to http://webaim.org/discussion/mail_thread?thread=3870.
The consensus seems to be that a site does not have to work with JavaScript turned off as long as one of a number of criteria are met e.g. that a user agent is easily and cheaply available that does support JavaScript.
As for using AJAX, it seems to be perfectly fine as long as all aspects of accessibility are addressed, namely
from http://webaim.org/techniques/ajax/.
WebAIM has a great follow up article showing ways to achieve these kinds of objectives at http://webaim.org/techniques/aria/. I would particularly look at the Dynamic Content Updates section which emphasizes the use of WAI-ARIA live regions.