Now concerning the flagged revisions. The current version has been implemented in Aug 2008 (before that, we had only flagged revisions for newly created articles). We only have the simplest review requirements: in order to be flagged, an article should not be vandalized, should contain categories, should have at least one internal link and a couple of more requirements. This is very useful, since it saves me a lot of time fighting vandalism in my watchlist, but we have not seen any increase in the number of editors because of this. We have about 500 editors (those who can flag articles) and about 500 autoreviewers (those whose edits get flagged automatically provided the previous version has been flagged); in some sense, these can be considered as "trusted users" discussed in one of the earlier threads.