I'm not certain of the diet or anything.
But I raised a baby flying squirrel once who had been thrown from a tree after big wind storms, and as for heat, if you don't want to be too hot, I recommend a new sock filled with rice. You can microwave it and make it the exact temperature you want. They keep heat pretty well too. At least enough to shower or do whatever else you need.
My squirrel would climb right on top of the sock and cuddle with it, since it felt like a big body.
I would recommend a dropper for the esbilac and pedialyte. I found that it was very easy to give too much with a syringe.