Can't speak for iTouch as I play it on a mini, but I can safely say its in my top 10 for GOTY. Got it the day it was released (iPad 2 at the time) and haven't regret it. If your an NBA fan, I'd consider it a must have.
Ouch. Wish I could help you there. I own an iTouch 4 too, but it's been collecting dust. I'd think with restarting the device (or using the System Activity Moniter app) to dump memory prior to playing as well as clearing your quick app switching trey prior to booting up would make all the difference...