1. Chances are good that the 4-pin CPU fan power connector got knocked out. You should check your connections because a motherboard wouldn't report that otherwise.
2. Yes - as long as all fans are operational the motherboard will adjust it accordingly to preserve system temps.
3. You'll need some 4-pin MOLEX to 3-pin PSU power connectors - they should look something like this:
You can pick those up at any PC parts store (Radioshack / Tiger Direct / Fry's, etc) for like $5 each.