@teeneythebetta, thank you so much. :) I'll probably start a thread once he's over here with updates, just in case anything goes wrong and I need to start asking people for advice.
And @Ilikebutterflies, that's a really good idea-- I have one heater currently that would probably work better in a smaller tank (it heats easily to 78, but I'd feel better at 80ish), and for some reason the 2-5 gallon heaters at my local petstore are less expensive than the 2-gallons-and-less ones. (I don't know why, haha.) So I might try that. :)