Here you go, you’ll be able to get any material settings figured out with a quick process.
As for the rest of it, there are as many answers as there are materials. There’s no good one size fits all answer to those things.
That being said, generally you want to cut hot and fast, meaning at full power at the highest speed that will cleanly and reliably cut through. This is less true with extreme materials (i.e. delicate or thin, particularly thick, or more/less flammable materials), or in cases where supreme accuracy in the corners is needed (lower speeds yield crisper corners, it has to do with acceleration, search “clean corners” and read up). It’s a very deep topic and there’s no shortcut to reading through the threads on what you’re trying to do as you go. Want to know how to engrave and cut cork? Search it, and read all the threads you find. Want to engrave tile? Search. Want to get a clean edge on birch plywood? Test and search.