Are you new to growing? Just BC you can have 26 plants doesn't necessarily mean you have to start out with that many. Edit: you could do like I did and start out with like 4 good seeds (or clones if you can get them) and 19 bag seeds, and try a few different soil types/mixes and whatnot to see what works the best.
If you are having problems with heat then put an air conditioner in the window of the room your grow tent is going, so you can at least keep the room cool.
I've learned the hard way that no matter how hard you try to treat your plants right, none of it amounts to a hill of beans if your environment isn't suitable and stable. I'm just glad I started out with mostly bag seed.