I use hovabator model #1583 and it has a fan. I use vermiculite in containers, but the fan does dry out eggs. Simple solution, cover egg containers with saran wrap and poke some holes with toothpick. I've never really had problems with fan motor heating up. The fan kicks in for less than 30 seconds most times, so I guess it depends on how cold the room is the incubator is in..
As for water to vermiculite ratio I've heard 1:1 always. I just mist mine till nice and moist and then let sit for 10 minutes to finish absorption of excess water. I also use my finger to make indent in vermiculite so the eggs are 1/2 above vermiculite, 1/2 under vermiculite. has worked good for me so far