I am a big fan of professionally built racks. I have a freedom breeder style rack, and a few pvc racks. I really like both. If you are going for heat and humidity, then the pvc racks are perfect. You will probably have too much humidity. A few holes melted into the sides and front of the rack will fix that.
Another reason that I like the pvc racks, is that they will last a lot longer than wood racks. If you think about it, wood mixed with humidity for a long period of time is going to start to rot. PVC is not going to do that.
There are a lot of companies that make pvc racks. I have personally bought from reptilebasics.com. They make really nice ones. The main reason that I chose them over the other companies, is that everything is included even shipping. The only thing that you have to buy is a digital thermostat, to control the heat.
I would suggest buying the 32qt rack. Some people keep all of their ball pythons in these tubs. I personally switch my big females into CB70 tubs. I keep all of my adult males in 32 qt tubs. You can also keep hatchlings in these tubs. They sell a tub divider, so you could keep 2 hatchlings in one tub.
I personally use disposable cage liners as substrate. You can use whatever you like. Most people use newspaper. I like the disposable cage liners, because they soak up really well, and are extremely easy to clean.
Make sure you have a heavy water bowl, because they will definitely tip them over. I use the 5" ceramic bowls. They are heavy and are rarely tipped over.
I do not use hide boxes, because the tubs are tight and dark, so I do not feel that they need the hides. A lot of my snakes will burrow under the cage liner.
Hope that answers you questions.