I like some of the changes (like the addition of initial status), but:
It is going to conflict heavily with Maint A
It has nothing to do with load prioritization, please don't use misleading names
I strongly disagree with storing avatar rez status outside of avatar class ( ERezzedStatus should have stayed in avatar class, it is as a part of avatar's internal behavior). If you need to, you can move it to some common 'avatar constants' or something like that, notifications are not directly related to this status
Please keep unrelated changes that seemingly do not affect functionality to a minimum it has been causing issues (ex: your cosmetic changes to LLToastNotifyPanel caused a crash).
I like some of the changes (like the addition of initial status), but: