Any tub will work. Just make sure you can close the top securely.

Flexwatt is the preferred heating method for those using rack systems because flexwatt is sold by the foot at a very low price.

If you are just using one tub setup, I would just use a UTH.

You need a thermostat specifically designed for reptiles. The reptitemp 500r is the most simple and inexpensive model but gets the job done. You absolutely need one of these if you want to use flexwatt with a tub.