welcome to the forum!!! you're off to a great start, as i see you have a thermostat listed.

the lamp needs to be on its own thermostat/rheostat as well. all heat sources must be regulated.

no aspen. aspen is very dry and, for a tropical species, is not good for ball pythons. use a coconut fiber substrate like you mentioned.

water conditioner is not necessary. if you can safely drink from your tap, then use regular ol' tap water.

i'd also invest in a spray bottle! very handy during sheds or if the humidity gets too low.