For tropical reef animals the average temp should be somewhere between 80&85F, a few degrees higher if you're only keeping Red Sea Animals, a little cooler if you're keeping Caribbean Animals. Stability is a lot more important than the actual temperature you choose.
As far as the Ick, increasing the temp will not help your animal and may actually speed its death. I suggest you set up a quaranteen tank and follow the hyposalinity proceedures outlined in the sticky at the top of the forum.