1. There are no "best" tools for sculpting. Honestly you can use whatever you have around you. Most professionals use handmade tools that work exactly how they like them, ground down from pieces of metal with handles of various materials. Mine are steel with wood handles that have been shaped and lacquered with polyurethane.
2. Sculpey is a good place to start. I use super sculpey firm, as it holds details easier than the regular super sculpey. It's easily found online or at Michaels. Monster Clay is also popular, as well as green stuff if you want to work with it. Honestly you can use chewing gums and sculpt with a rusty hatchet if that's what works for you. Sculpting is very individual.
3. If you want to learn how to sculpt, there are some resources online as well as courses. The absolute best way to learn how to sculpt is to just sculpt something every day. Look online at photos and try to mimic what you see. You'll be amazed how much your sculpting improves when you actually just sculpt something every day. Basics are easily learned online. If you want a tip, just roll a bunch of balls into the general shape of what you want to sculpt and go from there.
4. Super Sculpey stores well, but they aren't twinkies (kidding). Once you finish a sculpt you bake it (I torch mine) and then keep it somewhere safe once I've made molds. If you break it, it's gone.
Sculpting is something that you can honestly learn all on your own without any formal schooling (although it helps). Just sculpt what you see.
