The heat matt is ok where it is, I let mine sit about an inch above the substrate. And this way being a little higher up, as he grows and you have to add more cocofibre you don't have to take the matt off and reapply it higher. For the crickets yes you need calcium and D3 the lady at the store gave you wrong info, gutloading the crickets with calcium isn't going to be enough. You need to change his water daily even if he hasn't used it, and for the misting you want the humidity to be around 70-80%. For brands of vitamins Repashy makes good ones and so does Rep-cal.