If I run anySIM on my iPhone which is Activated and currently using AT&T for service in the US.

1) Will it continue to work normally with the AT&T SIM when in the US until I need to swap SIMs?

2) When I arrive in Italy, can I just purchase and install a prepaid Italian SIM and will it automatically recognize it and start working to make phone calls without any additional mods?
(Don't really care about SMS, I know Visual VM will not work, I know I will need WiFi for most, if not all, data needs)

3) Related to #2, Is there any additional procedure necessary to make the second SIM recognized and activated, hopefully without the aid of a computer?

4) Upon my return, Can I just re-insert the AT&T SIM and go back to that as my primary SIM?

I don't want to bring my Mac laptop with me so I am hoping to do all mods here before my trip.

Installer.app is already in place as well as BSD Subsystem and OpenSSH. I have Fugu on the Mac for file transfers and can use Terminal to initiate an SSH session.

Any help would be greatly appreciated.

For testing I can swap in a US / AT&T Go Phone SIM here to see if it is truly unlocked.

BTW, I will post the results of my experience when I return.