Welcome and congrats on your new performer. Start off with what you already have. Use your supplied Weber charcoal baskets and propane start on your performer. That is all you need for now to start charcoal. I find it works better than using Weber charcoal chimney as it has more room/oxygen around charcoals to start/burn faster. I do use the chimney but find it smokes more and takes bit longer to start ashing over. Learn how to use and position baskets for different cooks. You may find you don't really need SNS.
Bare bone minimal, Weber tong with long handle as mentioned, best quality meat you can find, good rubs, and quick check thermo. For low and slow cook, something cheap to monitor cooking grate temp for now. Just enjoy and mastering charcoal cooking first than other accessories will follow after. Just my opinion.