yes you can
Worked for me
no
Yes, use your friends'.
Although Apple would like you to think otherwise, if you unlock the iPhone you can use it on any GSM-based carrier (in the US, that means AT&T or T-Mobile).
You will have to first get the phone unlocked.
A black iPhone 4
In theory, yes. T-Mobile is actually the carrier for the iPhone in Germany. Keep in mind, however, that unlocking an iPhone completely voids its warranty, and if anything happens to it, the only recourse is to purchase a new iPhone. Apple will not service a broken iPhone if it is unlocked.
NO, iphone 4 from verizon does not have SIM CARD its CDMA its a NO!
No
Yes you can
Blackberry and iPhone
no you can use the mobile network for Internet