I have some tubs that I used a soldering iron on and some I drilled. If you drill just becareful not to carck the tub. When I was done drilling I went back over all the holes with a razor to make sure there were no edges. I like the look of drilled holes better personally and only do it that way now but using a soldering iron is eaiser and faster imo.
I use paper towels for my babies to sub adults then I use newspaper when they go into their adult 41 qt tubs personally. I am a clean freak so it is eaiser for me to keep everything clean this way. I also don't have to worry about my snakes getting substrate in their mouth etc. I do not have humidity problems in my tubs but if I did I would consider using a substrate.