So Im new to this cosplay.com and just saw this thread I actually used to work at Disney and attended MNSSHP alot.A few things to know
1.I dont think they can throw you out/make you change unless your like king mickey,donald,goofy,the princesses etc. and even then they would only do it if your costume pretty much looks better then there costumes or if youfor example dress as Snow White and start your own set and taking pictures,signing autographs they will throw you out.As far as Roxas,Sora,,and all other KH characters are concerned you should be ok.
2.Yes there candy choices suck they have been given some "healthy" stuff it kinda pisses me off but whatever.Anyways sometimes if you go threw the candylines and say your a cp they give you more candy
.lol if you don't know cps are college program kids that work at WDW and they dont get paid alot and are usually broke also if you really wanted to go on a busy night go in the lines every hour or so they are not gonna recognize you hell, you could every 20 minutes disney employees really dont care