Leds, humidifier, ac and all the trinkets
Damn, you should see how I roll. 
Heat shouldn’t be too much of a problem. With good air exchange and ventilation you could get away with it.
Wait until you have some vegetative mass before making adjustments.
No 
Channel the jeweler in you. Or poke a hole deep/wide enough to accommodate the tap root and cover with perlite. Mist.
Unacceptable. 
I mostly use this method to isolate sketchy cuts(bugs, fungi). The humidity is a bonus.
Although, once seedling emerge they don’t really need it. Maybe if rh is at 10%, but even then…
I give seedlings a tiny amount of nutes, maybe 300ppm, once, then observe. Autos don’t need anything the first 3 weeks.
As for watering, if you plant in a saturated soil, you’d be OK for a week, maybe 2. A dry-ish pot should be able to absorb 1.5 to 2 times its volume in water(in my case, can vary). The weighing method is a fool proof one, you’ll get a feel for it in no time.
Start higher and progressively lower them. I used anything from t5s to 1000w mh to veg seedlings and they love the light. (T5 2inches from the tops, 1000mh 4ft away for the first week)
I don’t know squat about led, so can’t offer any recommendation.
I wouldn’t use them, let them breathe.
6" or 3-4 sets of leaves. You can also check if the roots filled the medium. Not rootbound, but a good root system, and transplant then.