1. you'll need shorter bolts probably
2. It's probably a freewheel not a cassette hub
-take off the freewheel
-put on appropriate ss freewheel
-respace the the axle to get correct chainline
-redish the wheel
3. not really you don't want cx tread for riding around town but you probably want 32s at least for the trail
4. You can probably do it all yourself especially if you just buy a new ss wheelset($130) If you do take it to a shop ask around and find out what shops do conversions frequently.