I use wood pellet bedding ( I think the brand I use is ABM). It is safe if eaten and cheaper than Yesterday's News of the Oxbow stuff (I paid about $6.50 for a 35 pound bag). You can buy it at farm supply or feed stores if you have those in your area.
You can use a plastic stitching screen to cover the litter. Most craft stores have them and I have seen them at Walmart and dollar stores.
Wire grids can work if your bunny is a big chewer. I have even used wire cooling racks made for when you are baking.