As far as UTH go, they are safe for both the snake AND the wood dresser! As long as you use a thermostat(which you should anyway).
Think about how hot that thing would have to get to burn wood, like 180-200°F? How would that feel on your snake?
If you are going with a glass aquarium, and a screen top, you'd be cheating yourself if you didn't do some type of under tank heat.
As far as substrate, people use everything from newspaper, paper towels, Cyprus mulch, potting soil, aspen shavings or chips, coconut husk etc etc. personally I use Eco earth in some enclosures and pine shavings in others. Basically as long as it isn't cedar you should be ok. Obviously research whichever substrate you choose to use.
As far as tank size, there is no such thing as to big. Busy it up a bit when they are younger and take stuff out as they grow. They need to feel secure, but give them the option to venture out if they want. Africa is a big continent and they seem to do just fine there haha.
Sent From an Enclosure