1. Yes, they can.
2. Incomplete conversion would lend me to think that A.) your PH is really jacked, B.) You decocted too thin of a mash and left too few enzymes in the main mash, C.) Your thermometer is reading way high, or D.) (unlikely) you got some really poorly modified malt. The cloudiness I wouldn't worry about - you get a lot of proteins with a decoction. It will likely clear out in no time.