Planning to get a betta fish and would like some help

A few years ago I had a veiltail betta that unfortunately died when my tank got too hot, my old place had terrible A/C. After that, I decided to step away rather than risk losing another one.

Now I'm in a new place with better A/C, and I'd like to try again. I want to do it right this time, so I have a few questions.

Here's what I already have:

- 10-gallon tank (I heard that bigger is better, but I don't have much money for anything bigger yet)

- Heater

- Hang-on-back filter

- Thermometer

First, is there anything else I should be adding to this setup? (Well, other than plants and the sand.)

Second, what type of betta would you recommend for the smoothest experience? I know the fancier long-finned varieties can be prone to fin damage, so I'm leaning toward a short-fin type. Also, would a king/giant betta be any different care-wise compared to a standard-sized one? Those big ones just look so fat and funny to me and I want one.

Sorry if these are some basic questions, I just really don't want to make the same mistakes again now that I'm in a better position to keep one healthy.