2. Yes, you can just use under tank heat. It’s currently all I use right now. Except for during the day when I switch on the heat lamp. But that’s not for heat, just for light since my room’s window is covered up and I want my bp to have some sort of a light cycle.
To do the warm and cool sides, you just have a heating device on one side of the tank, and it should create a heat gradient. I have a heat pad under one side of the tank, which heats the warm side. Then the cool side will be around 80-84 degrees. Usually the cool side is within a few degrees of the room temperature. That’s why it’s good to try and have the room your bp is in to be 75-80 degrees.

3. You control the heat gradient with a thermostat, I guess. A thermostat will control the temperature your UTH puts out, making sure it doesn’t get too hot or too cold. As for controlling the cool side, you can either keep the ambient temperature in the room at 75-80 degrees, or add another heat pad on the cool side, and keep it at a lower temperature with another thermostat.

4. To start a tank, you need a tank, of course(I prefer rubbermaid storage containers). Atleast one hide for each side of the tank(clay flower pot bottoms work best, IMO), a water dish, substrate(newspaper is easiest probably), a nice secure lid(I weigh mine down with chunks of cinder blocks on each corner), and a heating device.
As for the 75 gallon tank, if you ask me, that’s too big. Ball pythons can stress easily, and prefer smaller more secure enclosures. A full grown bp can be comfortably kept in a 30 gallon breeder tank, or basically a 3 x 2 rubbermaid(thats what I’m getting soon for my bp). You’ll probably find that a 75 gallon tank will be much harder to heat....and cleaning it would be a pain. Lugging around a big glass tank for cleaning every month or two, lol.

5. When you first get your bp, you should keep handling down to a minimum(maybe hold it for a minute or two when first getting it home) and place it in it’s new tank to get accustomed to its new environment. Leave it undisturbed for atleast a week, so it settles in good. Then after a week or so, try feeding it an appropriately sized rodent. By appropriately sized, I mean a rodent that’s as thick as your snakes thickest part. When I first got my bp, she was 2 months old, and took a frozen thawed adult mouse.
Once your bp eats for you, leave it be for a few days so it can digest it’s meal, then you may start handling sessions to get the bp used to you. I recommend keeping the handlings to short sessions at first. Maybe 5-10 minutes. Then go from there, and you’ll find after some handling sessions, your bp will feel more comfortable with you.

6. That’s a totally unanswerable question, lol. It depends how old the BP’s are, I guess. All breeders have different aged bp’s for sale. Some could be hatchlings that are just a few weeks old...some could be years and years old. Usually though, the older the bp, the more expensive it’ll be. The older it is, the more money and effort that has been put into the snake to grow and be kept healthy.

Here’s a few pics of my bp’s cage, if you’re interested.

If you want to spend less money a Ball Python could be housed in a 10 Gallon until it is breeding age. Yes a undertank heater is fine. To control temperature on each side well.. the side with the heatpad obviously is going to be hotter then the one without it, but if you are like me and have 7 reptiles in your room, and your room is at a ambient temperature of 75-80 degrees. You dont need to worry about the cool side.

The lay out of the tank is confusing to me.
One end needs to be a lower temp while the other end a higher temp.
No, one end needs to be around 80 degrees and the other needs to be around 90 degrees.

3.How can you really control this?
By using digital thermometer, reliable heat sources, and a thermostat. It is easier than it seems.

4.What type of things do I need to start the tank? I’m getting a long 75 gallon tank.
Tanks should only be for temporary use. Aquariums SUCK! I sugest get a sterilite type container. A 75 long aquarium is way to big for hathclings and most juviniles.

Any photos of your tanks will help greatly so I can get a clear Idea of how to set up.

5.What do you feed your Bp when you first get it?
I suggest rats (preferably FT) taht way you never have to make the switch.