You want to get a tub that is around 6" tall. As for heating, UTHs should do fine from everything I've seen. Most people recommend flexwatt over a UTH, but if you're only looking at a single tub I feel the UTH is a simpler solution. I'll be getting one for the 34qt tub I just got, but haven't quite decided yet what size UTH I need. I think they should cover 1/3 to 1/2 of the tub. Drill/melt a few holes in the tub for ventilation and it should hold humidity and temp well!