If you're really worried about his weight you can always add reptaboost or zilla caloric to his diet. They can both be fed by syringe and have added nutrients. You can find them at any local petstore or can order them from ebay or amazon.
I really like roaches they are easier to care for than crickets and my beardies seem to enjoy them more! I am always fighting with my fiancee though about keeping them in the apartment.
I have kept all my dragons on paper towels for about 6-9 months of age and the moved them over to walnut sand (found a pet stores). All my dragons really like to burrow in the sand. I know it's a hot topic issue sand vs. carpet but I think it depends on how clean you keep the sand and the behavior of your dragon.
You could also try small horn worms! All of my beardies go crazy for horn worms especially and wax worms are a close second. I hope this helped!
Yes, that is a great help. I haven't been updateing, but in the past 3 days he has eaten 15 reptiworms per day . He is looking fatter every day, and I am starting to see his tail start to fatten.