If you don't feel like switching tubs once he is a little bigger, go with the 32qt and make sure you get two snug hides.
UTH? I've used a bunch of different kinds.. exoterra, zoomed, flexwatt. They all work fine as long as you have a good thermostat. Don't bother with the BAH-1000DC. Get yourself a herpstat intro or a Vivarium Exotics thermostat. The herpstat is the best. I have both herpstats and VE's and I love the herpstats way more!!