Aww, he looks so cute with your daughter!
There really isn't a set number of feeders he should be having, just whatever he will eat in 10 minutes, twice a day. That will probably work out to about 10-20 crickets each time or maybe even more. I don't know how many roaches he'll eat, but it should be on the same schedule...no bigger than the space between his eyes, as many as he will eat in 10 minutes, twice a day. As the roaches don't jump or climb, you can leave them in his bowl after the 10 minutes is up for him to snack on throughout the day. These guys get through a LOT of live food!
And please stop feeding him mealworms, they aren't especially nutritious, and have a hard chitinous exoskeleton which can cause impaction.
I'm not sure if you've seen this chart, but it's a very good one for working out what your beardie needs. Greens are great as a daily staple, but raspberries and grapes shouldn't be fed daily. If you want to add some colour to his salad, you could try some butternut squash.
http://www.beautifuldragons.com/Nutrition.html