Even if you get a detail from someone, I think it's a good idea to get an orbital buffer. Nice to have and can apply some wax in no time. Harbor freight even has one at a low price...a good option if you're rarely going to use it.
And for a medium compound, I like Meguiars Ultimate compound. Nice and cheap, like $9, and available at the likes of target. It replaced Mezerna SIP for me, but not a good choice for a one step.