Bolstering
Bolstering works and it makes the 10-49 bracket not only get queues quickly, but it also makes them quite enjoyable. Making it more tier based will severely hinder the ability to pvp at a lower levels. Even as a level 20 healer I felt very useful in the BG (I'm level 48 now). They may consider bolstering hp and perhaps resource regen based on level, but even if they don't it's still fun.
Premades
The premade vs premade is a good idea, but don't punish people who simply queue with a friend. I would say that if you choose to queue with 3 other people, then yes you should be in with others that choose to do this. Otherwise keep it as is.
Battlemaster vs new level 50s
I haven't had the "pleasure" of dealing with this yet, but I will in a couple of days. However, if it's as bad as people say then I don't think the fix is separating out the battlemasters. The fix is to lessen the gap between the two.
Queue times
You may not mind long queue times, but it is the one and only thing that kept me from enjoying pvp in WoW. I was a full time raider there. Here, I've leveled up my toon purely in warzones because I enjoy the pvp so much. The way Bioware has handled pvp queue times has been phenomenal.
Random Warzones
I actually liked how Blizzard did this. You could either choose the default (random) or you could pick which warzone you wanted. You just had an understanding that if you picked a specific warzone, you'd have a longer queue time. This solution worked quite well. That said, there need to be more warzones that can be same align vs same align. It can get tiresome running hutball over and over again, but it's better than just sitting there waiting in queue in my opinion.