Running the incubator for awhile is not a bad idea so you can fine tune it before you put eggs in it. As far as the vermiculite staying moist, if you spritz once a week youll be fine. You dont need to change it out. Now if you go with the raised method i got no help for ya there cause i dont do it and never have. I dont have anything against it, i just dont use that method. The best thing to do is research all methods and choose one that works for you. Another option that some have good luck with is maternal incubation. Though i think that method has the most room for error in captive breeding.