Will the snipe happen if the device is sleeping or off? Just wondering because I do not know if the sniper timers are on a server or not.

Once you set your snipe, you don't need to be online for the snipe to actually work.
That's the whole idea of it -- you can snipe and win even when your connection is bad or off.

I think it may need to notice somewhere on top that you are using 2 parts - 1 is server side, and another is software (and browser). So software is needed only to send info about sniper to server like a mail client maybe this make sence for many same questions about the same.

It is mentioned in the FAQ: http://www.myibidder.com/login/faq/1/#q5