76-80 is just fine. I keep my corns at room temp, which is about 78-80 during the summer and 65-70 during the winter. So you don't need a UTH.

For food, feed her something that is ~1.5x the widest part of the thickest part of her body. Feed her that once a week until you no longer see a lump. Then move up to a bigger prey size and repeat the process - once a week until you no longer see a lump. And so forth. Stop once you hit large mice. Even if you don't see a lump, they don't need anything more than a large mouse once a week once they're adults.

From the pick it looks like you can see a lump from when she was fed. Whatever you fed her, keep feeding her that until there's no lump right after you feed her. Then move up.

As for a mate, you snake is homozygous for anery and amel. If she's a motley het stripe, that means she has one copy of motley and one copy of stripe. Motley and stripe are on the same locus and are allelic to each other with motley being dominant.

If your sun want's something red and orange, get an amel stripe, maybe an amel stripe het anery. In the F1 this would give you amel motleys het stripe and anery and amel stripes het anery. There are lots of options depending on what you want to make and produce.