3 hours with full 3D, max brightness and wifi is fine. I imagine I'll get double that out of normal use.
Exactly, I always used to have wifi on when I had my DSi but it lasted a lot longer with it off and the backlight on half.
Also regarding piracy on the 3DS, I read a week or so ago that their is a White list for DS games, all they've done is add the name of the cartridge to that whitelist and it works, as far as I know it's only DS games so far and not 3DS.