I like a half-sand, half-soil mix for my ackies.
I personally wouldn't use a heat mat with them.
UV: If it's a second-hand viv, it might be a good idea to change the UV tube now. You don't know how old it is or whether it is still giving off any UVB. The heat bulb, you'll know when it stops working because it'll ... stop working
As for cleaning, I'd clean when it needs it; using a reptile-safe disinfectant is a good idea.