Does it look like she's getting any quills back in? If not, I'd head for a vet visit. Dry skin and quilling don't generally lead to an area of thinned or no quills, so it's possible she could have mites anyway (especially if she's on wood bedding), or a fungal infection (someone else recently went to the vet for what seemed to be dry skin, but turned out to be a fungal infection).
Yup, she's just being defensive. Make sure you continue to get her out each night for at least half an hour. Letting her stay covered up in a blanket may help her to be more comfortable for right now while she's getting used to the new place and a new owner. It was good to try putting the t-shirt in there...just leave it in & she may come around.
Also, I'd really, really recommend taking your location off your profile. Hedgehogs are illegal in PA, and everything I've ever seen says that PA is the worst state regarding illegal hedgehogs - people are actually afraid to even drive through. I'm not sure if it's still that bad, but we really don't recommend owning hedgehogs in illegal areas on here, so it'd be good to at least avoid advertising the fact. Make sure you also can get her to a vet out-of-state if necessary to keep her safe and give her proper medical care.
Lastly, here's a great book with lots of information that I'd recommend checking out. It's free to download - http://www.westcoasthedgehogs.com/fi.../download.html