77F should be fine. Get him fat and sassy with those live foods and then the small size NLS pellets should work good (or the flake works too). I'd go with tetras over barbs, just like to avoid pangea tank whenever at all possible. You could get real crazy, and try to find tetras from the rivers that Aggies inhabit in the wild. But get him some friends to feel safer, and get him a cave of some kind to hide in, even if it's just an old coffee mug-for now. He's probably too concerned with his safety to eat well.