Can an iphone 4 be used like an iPod touch?

Need specific but clear answers. First, I do no care that buying an iphone without a contract is stupid reason and not activating it. I want to use the iphone 4 as an iPod touch. Now my questions:

(1) can it be used without it being activated at a home company?
(2) does the Wi-Fi still work?
(3) does all the other apps still work, especially imessaging?
(4) what else should I know?

The only thing on your list that won't work is imessages

Imessage should work over Wi-Fi also.