I have no experiance with eggs or breeding, but from what I have read, eggs will feel like impaction spots; small and hard. If you think there's the slightest chance she might be gravid, prepare an egg box. If a gravid female doesn't have a place to lay, she will hold her eggs, which is called egg binding, and can be fatal if surgery is not performed immediately.
Here's an article on eggs. Go to the "laying box" section. There is also a section on egg binding that would be good to read.
http://www.bio.miami.edu/ktosney/file/BDeggs.html#Anchor-The-47857
You won't have to worry about incubation or anything; unless she has been with a male, the eggs will be infertile.
Husbandry sounds good. I reccommend bumping the cool side temps to 80*F (26*C) and the middle area to 85*F (30*C).
What brand of calcium are you using? How often?
Apples aren't very healthy and should be fed occasionally.
Here's a great food chart that lists good greens and veggies to use as staples. There's also some helpful supplemet info at the top for gravid and nongravid females.
http://www.beautifuldragons.503xtreme.com/Nutrition.html
You're right; scratching and digging is often observed in gravid females. However, it could also be that she just wants to sleep in a burrow.
As it is summer, I doubt she is attempting to brumate.
Parasites are a possibility. It would be a good idea to take a fecal sample to a vet just to be sure. My beardie came to me with parasites, and as a beginner, it was many months before I realized something was wrong.

He is still being treated with numerous meds. Trust me, if your beardie does have parasites, it's best to get her on treatment earlier rather than later.