Hi, Here's my best advice for substrates.
For young dragons, I use some non adhesive shelf liner. You can get this at Target or WalMart. I like this best because: It's super easy to clean (and young beardies poo alot); it provides a bit of cushion for adventurous young BDs who like to jump from the tops of basking spots, plants, ect.; it comes in a neat tan color that looks great in the viv; it is easily cut to fit whatever size enclosure you have and it's cheap.
Playsand should really only be used for adult dragons over 10 inches in length. There is always risk of impaction. If you do use playsand, I recommend washing it with clean hot water thru a sifter to cut down dust. You can bake it after washing it to ensure all moisture is gone, this will also sterilize it.
A piece of slate or rough tile in your viv will naturally help keep claws manageable too. I clip nails on my larger dragon though.
For the crix, just throw a couple pieces of raw potato and a bit of whatever your salad of the day is.