My rooomate wants to change out his Ultegra 9-sp triple with a Compact FSA Double that a friend gave him for free. This is on a 04 Trek. I have talked to 6 dif mechanics here in San Diego and got 5 different answers on various questions. I know I need to change out the front deraileur to a double but here is the fuzzy parts.

1. will a 10 spd double work, or do I have to find a 9 sp double.
2. will his triple front shifter work with a double (most mechanics agreed it could be rigged)
3. will his long throw rear deraileur work?

Anything else I missed?