i wanted to know if the creeps in the caves ever respawn

also if i killed a count will a new one be elected or will the town remain leaderless

Yes they do respawn, You can't kill counts

The normal respawn time without any mods is 3 days. It is possible to kill certain Counts or Countesses at certain points in the game, though not all of them. The town will remain leaderless if you do so.