Ok....wow....
1. 86+ will inhibit Ich reproduction and speed up the current lifecycle, and at I BELIEVE 88+ the parasite cannot live which can result in the infestation being cured if the particular strain isn't heat resistant as mentioned.
2. Salt is fine in a planted tank as long as you don't overdose. I would recommend ParaGuard-safe for plants, inverts, and scale-less fish in my experience and I've used it with all 3. Cures ich easily in 7-10 days and no possibility of a repeat outbreak if you treat fully in combo with salt and heat, plus you'll be cleansing your main tank instead of worrying about QTing the fish AND sterilizing your display.
3. Ich will not lay dormant more than several days in its cyst stage, however I still recommend not taking any chances and "nuking" the tank if you will with the treatment I mentioned.