The armor I see as more of a LoD thing than a TAV thing specifically but they're the ones the armor is most associated with. Xehanort and Eraqus wore...
I would also like Monster's Inc. to be a world. Considering doors being an important part to KH (door to darkness and such) all of the doors they use...
Like it was said above you can view the scenes whenever you want but apparently if you watch the scenes before playing Re: CoM you can get keyblades...
Hard to say mostly because I don't have an emotional bond with most of the characters. Or even if I do KH being still being a generally upbeat series...