N70 & General BB5 Questions

My long-awaited N70 finally showed up yesterday, and I'm loving it so far. I'm a picky user, and can always find something I don't like about a given phone. So far my complaints have been minor with the N70, but I have a couple questions for current BB5 owners:

1) Sadly, I'll probably never use the UMTS capabilities of this phone, as I'm in the US. Will I notice any difference (I.E. Better battery life) if I switch it to GSM only instead of dual-mode?

2) Once again, being in the US the front camera is more of a novelty item. Any practical usage for it besides the occasional low-res self portrait?

3) On my past S60 phones, hitting the End Call button takes you back to the home screen, but leaves the app you were in running in the background unless you open the task manager and close it manually. Some apps are closed when I do the same with the N70. Any rhyme or reason to which ones close what I hit End Call and which ones stay open?

That's all for now. Thanks in advance for your input