The "high technology" sensors (as Apple calls them) in the iPhone are some of the more exciting features this new device brings to the table. These sensors won't result in the iPhone doing anything other phones aren't capable of, but it will let the iPhone do it without instruction from you.
The proximity sensor:
Yes, the iPhone will work overseas, and not just in Europe and Asia. The iPhone is a GSM (Global System for Mobile communication) phone. GSM, which uses narrowband TDMA, was first introduced as a standard in 1991 and is now in place in over 100 countries.
Access to receive and place calls from outside the United States will require additional services from AT&T/Cingular, which you will need to arrange with them before your phone will operate in such a fashion, but the phone is perfectly capable for worldwide use.
Yes, fortunately it does. The iPhone is equipped with a connectivity port just like that of the iPod. This means that the iPhone will connect to existing iPod accessories like car docks and speaker systems.
On your iPhone, when the iPhone is released and you go buy the iPhone at a licensed Apple or Cingular retail store.
Just kidding. We found a nice, high quality version right here (and it's free):
Update: See this FAQ to make custom ringtones using iTunes.
At this time, the only way to use custom ringtones on the Apple iPhone is through a somewhat complicated hack.
Apple is rumored to be planning custom ringontes for a coming update to the iPhone.
