Well most tetras are tropical, but are you going to keep most of them? That's not a good idea, stick with 1 to 3 species, depending on the size of the tank.
Depends on the tetra, but average temps would be 75F range. That said, there are those like rummynose and cardinals who prefer it warmer. And some who like cooler.
If you want a lot of good info about Tetras, go to this link. It keads to 7 pages of tetras with in-depth info on each one. I consider thie site of of the better ones for quick reference for the average fish keeper. https://www.seriouslyfish.com/group/tetras/