I think the official rules do say--or used to say--"Costumes must not be overly theatrical" or something to that effect. But you'll need to have a majority of judges protesting to get a costume violation (just like with lyrics violation), right? Hopefully your costume isn't so bad that over half the panel wants to ding you.
And no, Kurt didn't get 6.0s in technical merit for that performance. But 5.9s are pretty darn high for something that should've gotten a mandatory deduction (even if it's once rather than twice), so I can't figure out if the judges started at 6.0 and deducted to 5.9, or if they just forgot to take the deduction. Viktor did make a small error or two in the beginning, so I can see why Kurt won. But what on earth would the judges have given Kurt if he'd landed the quad? 6.2?
Btw, speaking of Kurt and quads, does anyone know if he landed a clean quad again since the historic one in 1988? I know he made a few attempts, but the ones I found were all two-footed or tripled. (Clean = 6.0 clean--no step-out/two-foot/hand down/fall, but wonky landing or slight turn is okay).