I cut my own rifle lean racks from MDF. Done it for 3 safes now. build it deep enough so that scopes do not rest on the back wall of safe. It also doubles as a small shelf for keys, cleaning products etc. They are just tight press fit in... so don't cut the width too small. Just angle into place then tap it horizontal with a hammer. also figure out how many guns you can theoretically fit (ie a 5 gun safe is usually 5 guns without scopes as they fit closer together. maybe 4 scoped or 3scoped +2)
As for lining the safe, carpet off cuts, industrial carpet squares, heavy felt, rubber sheets from clark's.
you only have to line the areas that might damage the rifle eg butt and scope area. The rack keeps the barrel off the wall. Don't forget to line the underside of the ammo storage/roof- protects the muzzle when lifting the rifle out.
As for lighting... those portable 3LED light Pucks with a magnetic base. Touch click on and off and use 3AA batteries. Can get them from any supermarket or Bunnings etc. Stick them to the inside of the door or roof of safe.