For lighting, you'll need to decide if you want a FOWLR (fish only, with live rock) tank, or a reef tank (with corals).
A thermometer would be any one that you find, basically.
The sticky at the top of this forum has a lot of info about how to set up a nano tank. If you can, get some of the recommended books, they'll save you a lot of trouble and expense when setting up a saltwater tank.