You can use a tiny amount of sand from the old aquarium as-is in the new one in order to help seed the dead aragonite sand and start the cycle; by the way, when I say tiny, I mean maybe a cup or two.
You shouldn't need a chiller unless you run MH lighting; T5's and LEDs have a negligible amount of heat transferred to the aquarium itself. If you have no intention of adding corals any time soon, then you don't need to go all-out for your lighting. However, everything will look way better if you make sure that you have both standard high intensity daylight bulbs/LEDs and actinic bulbs/LEDs; the colors will really pop with the addition of the actinic lighting.
Painting the back black or blue will look pretty nice, so I say go for it. If you want a less-than-permanent solution, then get a nice plain background that can be attached to the back.