Can I suggest that a fully Moodle-integrated Questionnaire Module may be another potential outcome of this code sharing project.
I'm not sure how easy it would be to replace the current php-esp questionnaire 'engine' with something that shares a lineage with Lesson and Quiz but it's something to think about anyway.
Of some relevance to this discussion is the Oracle compatability layer being developed for Firebird/Interbase with the supremely odd name of Fyracle.
This allows you to move to a solid open source solution even after your snooty DB admins have attempted to lock your project in to an expensive proprietary solution.
I think I experienced something similar, I thought it had been fixed though.
There's two different ways to mark up labels for forms.
You can use the label for="id", or you can contain the relevant form section inside the label tag.
You can read more than you probably ever wanted to know about accessible forms in this book chapter
To answer your second question, I don't think there is an 'accessible version' as such. Moodle is already accessible for a wide range of users and continues to focus on improving its accessibility, as well as it's usability, security and pedagogic flexibility. None of these aims have obvious finish lines though each release is (hopefully) an improvement and so the next release (1.5) should be more accessible/secure etc.
That may seem like a cop-out but in my opinion it's the only truly honest answer, and you'd presumably get the same answer from any other website/service that is seeking to be accessible. I would be suspicious of anyone who claimed they were "accessible enough" and had no further room for improvement.
Of course if you have any specific problems with the accessibility (or security, usability or pedagogy) of Moodle then you can always discuss it in the forums, enter a bug report or make suggestions for improvement.
Note that ordered lists (<ol>) can be styled with CSS to provide a number of different styles without touching the PHP or HTML (view source for details):
This might be something to move towards in the future.