First slug of RV supplies for a first timer. What do I need?

Forget the RV TP........regular TP septic safe is OK
RV TP is 'high priced' thin tissue paper.....used to lighten your wallet and to wipe your finger with after pooping

Waste tank chemicals.......just use dihydrogen monoxide :B

IF your black tank has a built in flush system.........standard garden hose and a "WYE' to connect potable (drinking hose) and garden hose to CG spigot