We keep our adults in 4' long x 2' wide x 2' deep enclosures. I'm not sure, but I think that's a bit larger than a 60 gallon breeder tank.
As for their greens and veggies, mustard, turnip, and collard greens are good, as are any of the squashes, yams, zucchini, and some occasional non-citrus fruit. A great place for dietary stuff is
www.beautifuldragons.com You will find a list there of almost every type of food you could ever want to feed them.
It's great that you're checking into this stuff before hand!
Oh, and you had mentioned sand before...we used to use sand, but switched over to ceramic tiles in our enclosures and LOVE them!