Each beardie will be different. Some will eat more than others. Just let him eat as much as he can in about ten minutes, that's a good general rule to follow. Make sure the insects are no larger than the space between the lizard's eyes.
We just talked about salads a few days ago so I'm gonna copy and paste my post. 
go to the Nutrition Content section of this web site
"She has the foods color coded so you know foods listed in green can be fed daily, foods in black can be switched around for variety every few days, foods in blue can be occasional treats, and foods in red should be avoided all together. I've got her website in my favorites menu and I reference it every time I want to try something new for my beardies.
Personally, I use either collard/mustard/dandelion/turnip greens, endive, or escarole on a daily basis (whichever looks freshest at the store when I buy them). Then throughout the week I will throw in some yellow squash, kiwi, mango, raspberries, bok choy, or green beans for variety. 3-4 times a week I mix in some moistened rep-cal pellets for extra protien and fluids. My beardies LOVE their salads and they are fat and sassy.
"
-----
Amanda
------------
2.0 bearded dragons (Ocho / Domo-kun)
0.1 kingsnake (Rio)
1.0 ferret (Playstation)
1.0 cat (Wally)
0.1 dog (Tima)