Hi Tammy,
I can't really answer the 1st question, since I don't know much about it.
For the revisions. The real problem is not the data model scalability but more of a UI scalability. After much debate on it (see chat logs). We have decided that it was more simple to put one button. That is "Save" which makes a new revision. Rather than "Save" (no new version) and "Commit" (new version).
Anyway Mark and Carl is leading the CMS UI, they should shed more light into this. I am not fiddling too much as the revision decision has very little to do with the backend involved.
