IT doesn't need to heat up to where it feels warm to your hand; it's supposed to keep the soil at a temperature lower than body temperature so it stands to reason it woucln't feel very warm to the touch.
Ideally, one strain per reservoir. Or multiple COMPATIBLE strains.
Close vents if plants wilt. Otherwise, use them to prepare plants to have the clones removed entirely. It's called hardening-off. The plants under domes have been rooted for less than a week and need some added protectoin.