Not able to queue for instanced pvp yet but there is something new now. When you disable your experience you get a buff that tells you are exp locked with a red bandana picture. There is totally not any reason for making it like that and it might be to not confuse players in some way in battlegrounds. I just don't see any other reason for this change. But this is just speculation and not a fact.
I still have some concerns myself about brackets in general. Wanted to point out that blizzard just simply should give characters their skills at level 20 for example so everyone in a bracket has acces to the same skills (most skills are already available before level 60) and you point also at the battle for gilneas. There is just no point in having acces to that half way the 20-29 bracket. I was waiting to make some sort of feedback when instanced pvp went active on Legion Alpha/Beta for low level on the leveling realm. I even believe that it's a good idea to have the battle for gilneas at lvl 10 now. I can understand why they made it lvl 24+ though because it was a new battleground and they didn't want to make that available for trials, just like not giving acces to exp locked battlegrounds at level 19. You can see that trials only have acces to classic battlegrounds, maby they will lower it now since it's not so new anymore.
I am not able to do anything with tabards and shirts yet through the wardrobe. I have 2 in there of both but I am not able to transmog any or take one out and equip. Not sure what you mean with shirts getting soulbound though but I suppose you mean when taking one out. Time will tell.