Erm, you do mean Anime Festival Asia right? haha ^^,
I was there too, both days!
Pic 1) If you shoot in raw, you can change the photo's Temperature in Photoshop Camera Raw. And while you're taking your picture, you have to set your white balance to about Tungsten. One more thing. You can use Flash even if there's glass, but remember to shoot it at an angle so that reflected light will not go back into the lens.
Pic 2)The cosplayers are dark because the light is coming from the back (Window). two ways to solve this. Either use a Flash to fill in, or set your metering mode to spot and meter their skin.
Pic 3) lol @ expression, cool!
Pic 4) Asumi!!! lol, she's really nice. Costume is actually done by Sakurazaki (a member in our NP's own JTC Cosplay division)
Pic 5) heh, ofcourse give plastic peach to judge..the judge probably is Kaname, a very popular Japanese cosplayer. Nice take, she's cute.