1. The Cop. Second would be The Mayor or Doctor, depending on how the game goes.
2. Tough choice. Mick can kill, but has to last to the bitter end. Clark can only kill once (potentially), but only needs three people gone. Important: Neither can win while the other lives.
Early on, I'd say Clark is more dangerous, since he could win at the end of N1 at the earliest (if everyone used their kills and happened to get all of his targets). By my calculation, the earliest Mick could win is the end of D2.