Hi,
1. You need your provisional license in order to schedule the theory test.
2. I sent my passport (recorded, with an enclosed pre-addressed/pre-paid recorded envelope for return), and got it back in about 10 days. This was last summer, though.
3. Not sure what you mean by "the whole process". You have to get your provisional license, take your theory test, and then take your practical test. How long it takes depends on how quickly you can schedule/pass the tests.
4. You don't need to send your US license.
5. Not sure, as I sent in my UK passport. I think a passport is the only thing they require, though.