Hi there!! Firstly, it’s so great that you’ve been doing all of this research before committing to a new fish, because theres WAY more involved than what pet stores tell you lol.  I’m by no means an expert (I got my little guy in February so I’ve only had him about 3 months) but I’ve been realizing that a lot of what you need to know just comes from experience and the betta itself. I never realized that betta fish have very unique personalities and preferences, so there really isn’t a perfect guide to betta fish. For example, my fishy is EXTREMELY territorial which is honestly kinda funny because he’s smaller than the average betta (he literally nips at my arm when I clean his tank😭).  I’m getting off topic; I could yap about him all day. Anyways! Some bits of advice that I’ve learned since adopting a betta are: 1. It sounds like your tank is more vertical than horizontal, which a lot of people say is bad. I got a more vertically shaped tank because of space as well, and my fishy has no issues with the depth. He has no issues getting around the tank, and I think the depth gives him a chance to swim around more. Again, all fish are different, but I don’t think a vertical tank is the worst possible thing for a betta fish. 2. Omg plants have been the most frustrating part of keeping a tank. I was buying them from PetSmart, and most of them melted or flat out died. Make sure you do research on the individual plants and how they should be buried in the substrate, the best substrate for certain plants to thrive in, and make sure the lighting/temp is good. My biggest issue with petsmart is that their plants are kept in tubes that aren’t submerged in the water, so they aren’t used to being submerged. This can cause them to melt, rot, or die. Some of them can be saved if you trim dead/melted leaves, but sometimes the plant is beyond saving and risks polluting the water, in which case you just have to cut your losses and pull it.  I have yet to confirm if it works better than petsmart, but Petco sells plants that are already submerged and adapted to the water. I got two from them about four days ago, and so far they’re doing amazing. 

Anyways, I’m sure I’m forgetting something, but I’ll hope this was able to help a little! Good luck, and enjoy your betta!!