I'll address the skinny situation first: You really don't need to fatten her up. Just a good, steady, healthy diet. I would do mealworms, crickets, butterworms, phoenix worms... a combo of those. Save the wax worms for a treat once a week. They last forever in the fridge anyway. I wouldn't let her gorge herself either. She's likely to regurge. Get some Repashy Calcium Plus supplement to shake on to the insects 2-3 times a week. I don't dust phoenix or butterworms bc they already have a high calcium content.
For shedding issues: I would provide a humid hide. We have this rock hide that I just put damp paper towels in. It's one of those two level hides with a magnetic peekaboo wall. Works well. Since you are talking about a stuck shed though, it may be a good idea to get a little tupperware and put warm, damp papertowels in that to see if she will work it off a little. I haven't had to do that though, so maybe someone else will agree or disagree, so as to further guide you.
Temperament: I think most are quite docile. I wouldn't handle her for about a week, then you can get her used to seeing your hand by just placing your hand in her cage and leaving it there for a few minutes. Then try petting her head and back. Then you can slide your hand under her. Then try picking her up. Slow and steady. Having said all of that, we have two. One is the tamest thing ever and one is a total spaz. The tame one will get right on your hand, the other will bite you. We did the same hand training with both. Hope you end up with a tame-able one and not a "guard dog" leo!!
Glad that she's got a caring owner like you now!!