Newbie grafting questions

Hi all,

I'm newly becoming interested in grafting and really want to create a multi citrus tree. I don't have any of it started yet and have some questions about Rootstock.

I don't necessarily need the tree dwarfed, but I wouldn't mind it either.

I think I could just plant some seeds I got out of a local lemon, and graft onto that.

Other options I see are buying a grafted variety and grafting further on it.

Do citrus cuttings root well? (I know I can Google that, it just occurred to me)

Anyhow, how do most folks go about getting rootstock and does it really matter what seeds I plant for it?