Well tstats are just a whole lot easier to use and some people here have had failures with the zoomed rheostats, I dont trust the rheostat with my collection so to me it was worth spending the extra money to have some peace of mind that I wasnt goin to have my house burned down or my reptiles fried.
I dont really think a heat lamp is neccesary it just KILLED the humidity back in the old days of glass aquariums, one uth on the hot side set to 90 to 94 should work just fine.