I'll take a stab at answering because I use the phone basically as you intend to. For me, it's a pocket sized tablet/camera/MP3 player/portable game machine, not a cell phone (particularly since it has a bad ESN and can't be activated with Sprint). So for your questions:
1) "could I right out of the box use the camera": yes
2) "or send email via a wifi hot spot": yes
3) "or would I actually have to purchase air time to even activate the phone": no, just bypass/skip the activation
As long as you have wifi you can hook into you'll have internet access. Recommend you add a microSD card for additional picture storage (if you intend take/keep a lot of pics). I'd also recommend putting it in airplane mode to disable the transmitters, then turn on wifi so that it's wifi only.
Hope this helps