If you raise the temp you lower the available oxygen, sometimes meds will require the addition of oxygen too, so you need to add additional amount to the tank with a bubbler and/ ideally lowering the water level a couple to few inches from the HOB filter out flow if that is what you have, so the water splashes down in there better, stirring it up with additional O2.
How's that for a run on sentence!
The temp needs to be 86 or even 87.
Salt and temp increase can injure snails and Cories, off the top of my head.
read up on the life cycle of the Ich there are a couple very good articles about it. This will help you understand.
Adding more fish can stress your tank. It would be wise to NOT add additional fish until you have completed treatment, returned the tank to normal parameters, changing out salty water a little at a time over several days pwc could be a week or two. Also decreasing the temp to normal over the course of a degree a day.
Then making sure they don't get anything else. Testing and checking to see that your tank is cycled. Some medications kill Beneficial Bacteria aka BB and that means you will need to almost start over.
Check with manufacturer about how much water to remove at the end of the treatment with meds.
Use a test kit to make sure you are running with correct/safe levels for your tank.
When everything is stable again after a few weeks of all normal you can get additional fish but they should be in a Quarantine tank, so they don't get your other fish sick, if they are sick.
Make sure to check your water for temperature to make sure it is not colder than your aquarium water when doing pwc. That can sometimes stress a fish and it will get sick.
Add fish slowly, a couple or small number of schoolers at a time wait a couple weeks, and so on.
I am tired, I hope I didn't leave anything out.
Usually with salt and heat treatment keep treating for 7-10 days after last white spot is seen in the tank (I did 10), meds are not necessary too.
