Hi! Man I wish my dad was still alive when I got into snake keeping but I think it's great you and your daughter are getting into a hobby together like this. For the new cage, I would definitely recommend a T8 for a ball python just make sure there's enough hiding room and it should be great. That's what I'm getting my BP for Christmas too lol. I have an exoterra for my bp rn, and while it is a great display tank and looks cool, keeping humidity in is such a vassal, I have to put foil over he top, keep moss in his tank, and spray once or twice a day. PVC is great because it helps with humidity, it's stackable and it looks pretty good too!!! One word of warning though, when it comes to stacking tanks, I recommend only stacking the same size tanks on top of each other as AP has said so themselves in an email that bowing may occur when stacking enclosures that are different sizes, so you should watch out for that cause you wouldn't want your snake's enclosure to collapse while they are in there lol.
As for the feeding, there's a pretty common feeding chart a lot of people on here (myself included) follow

Now you don't really HAVE TO use this, so if you don't want to, a good rule of thumb would be to go for a prey with the same thickness as the thickest part of the snake's body.
Now I'm going to assume that since you are a new snake owner, you are feeding store bought mice, if the snake is on live, I recommend switching to f/t immediately, it's more cost efficient, it's practically the same thing, and you don't run the risk of the mouse hurting your animal. If your snake is already on f/t, then I would recommend buying your snake food from Big Cheese or Perfect Prey online. Most pet stores over price mice CAZY and the most expensive part about ordering online is just the shipping but if you only have one snake, you get enough snake food to last about a year with just one order in most cases.
One last thing. When I first got into reptiles, I loved BHB and while Brian is a super nice guy, I wouldn't take his word on everything. The tubs he keeps his animals in are way to small in my opinion and he just has way too many animals for them to all be kept in good healthy condition. I've also heard of people buying from him and being sent animals that have mites or other issues. A great family friendly YouTube channel with beautiful animals is Josser'sJungle, I think your daughter would love that channel. Not to say watching BHB is bad, just might not want to use him as a role model per se. He is extremely kid friend and interesting to watch though so I can't blame anyone for being interested in his videos. He's had some amazingly beautiful animals on his show as well which is what drew me in at first, but you should definitely broaden your horizons and find more people that also like helping like AriAwesomeness of IG (he has a YouTube but I can't remember the name, it might be the same) I know him personally and he's pretty cool, takes excellent care of his animals and love to show off his anacondas.
Best of luck with this new hobby, I'm sure you and your daughter will love it, feel free to ask anymore questions if you have any, and sorry about the stupid long message!!!
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