I turn my phone off every night. Can't be woken up at some strange time, I'd probably never get back to sleep 
Does the iPhone even charge while it's off? I don't turn anything off at night. My MacBook goes into sleep mode and sits on the charger. My iPhone is at my bedside charging while on, and ringer on low, just in case there's an emergency.
Nope, it has to be on for it to charge. Even if you turn it off, once you plug it in, it turns itself on.
I concur with the 1-2% a night but I've never been able to get to a zero usage increase. My iPhone 4 always has about 10 minutes of "phantom usage" overnight and I can't work out why. I don't have email set up on the phone at all, calendar and contacts are on manual sync, notifications are set to "Off" at the top level of the Settings app, and I always switch to the home screen before putting my phone into standby.A properly set up iPhone drains maybe 1-2% battery over night, and "usage" won't go up AT ALL, not even 1 minute.
Yes and No plug it in then turn it off. It will still charge.
No, but my home phone doesn't buzz in the middle of the night when I get new emails. I am in the group of people who would love to be able to have automated notification profiles, but don't want to jailbreak.Work has called me at 3 am before, and if I didn't have the phone on, I imagine I probably wouldn't need to bother showing up for work the next morning. Also, since work pays my plan, it would be bad to have it off.
But... Why would you bother turning off your phone? Do you turn off your home phone every night? I suppose some people do, but it just seems like a bad idea to me.
-jt2