hey congrats on your snake!!
1. We use a UTH for our orange ghost who's in a 30 gallon and it works fine. just make sure you have a thermostat otherwise the temp on the glass can reach an access of 110 F. and if the burrow don (which they will) they can burn themselves on the glass. I recommend Herpstat (we have two and they work great) but I hear good things about vivarium electronics and Helix Controls.
2. Humidity is easy to keep up. what we find works great is we use a wet towel and keep it over half of the screen top. we rarely have to mist but if you find it drops too low just give the enclosure a little spray with warm water and it'll climb back up.You can also try a few tips that we didn't have to use but are useful. Keep the water dish near the heat source. Some People get a piece of plexi glass cut to cover 80% of the the mesh top trapping the humidity inside.
3. Substrate: Cocohusk helps to keep the humidity up as well. A lot of breeders use it for two main reasons. It helps hold humidity, and its safer to use when the snake is breeding because Aspen and Cyprus can damage the sexual organs or get pulled inside their body. I also found that the sake is less likely to injestt cocohusk accidentally when they're feeding because it won't get stuck to the feeder animal's body.
Also if your going to buy a hatchling or a juvenile make sure that you give him lots of decorations and cover to make him feel more enclosed and safer. We give him two hides 5 plants and driftwood.
Hope this helps.
Chris.