Welcome to the board, Danny, though I wish it were under better circumstances. So sorry to hear about your cat.
With luck, one of our more experienced cat gurus will be chiming in soon, but here's a thread by one member who has experience with CRF in cats, just in case you haven't already seen it: Early Stage Kidney Failure in Cat
. It's a long thread, but it's chock full of information.
I hope your kitty is with you a long time!