I generally take mine out separately. You could have them both out together you'll just have to keep a close I and monitor them to make sure he isn't being to aggressive.
Spinach has a calcium binder in it so it is good to give. Collard and Mustard greens are good. here is a site with info.http://www.beautifuldragons.503xtreme.com/home.html
It depends on the age. Younger ones will shed a lot more often as they grow. How old is yours? What kind of set up do you have? what and how often do you feed him?
I have used the slimline for years with no issues. You can change the bulb and put a reptisun in it. make sure the plastic cover for the light is taken off to allow the uv to get to your lizards.
depends on the kind of fake rock and the kind of real rock. rocks hold in the heat and help keep the cage warm for a while after the lights are shut off. Rough rocks help file down sharp claws.
put about a dozen in that are smaller than the space between the dragons eyes. after about ten minutes take out the remaining crix or add a couple if their isn't any left. do this 2 to 3 times a day.