I'll put out my experience with fixing cars professionally (while still keeping in mind that it's your money.)
First off, a swirl torch isn't what you want for rusted-fastener duty. They're great for heating a large area (for, say, bending/reshaping work), notsomuch for getting that stuck nut off (remember: the goal is to heat the hell out of the nut, getting as little heat as possible on the stud or nut.)
A welding torch (or, preferably, a cutting torch, as it gets you more versatility and control) is what you want.
A quick Google search find me this kit, which I think may be what you were looking at? If so, that's everything that you'd need, less tanks & cart (CART IS MANDATORY! THIS IS FOR YOUR SAFETY!)
As to the source of the heat: nothing can match oxygen/acetylene. Nothing burns hotter.