To help the polishing process, you can use any normal vibrating sander usually used for wood etc. The way we used to polish large jobs up was to fit an abrashive pad to the sander (we called it Birtex). You can buy them at all diy stores or places like Halfords etc. As long as your sander has clamps to hold the sanding sheets (or in this case the abrasive pad) in position, you're good to go. Then, as suggested above, use Autosol as the compound. With a sander, you'll get the floor done in no time. As you're sanding it'll leave a real dirty mess, but just wipe it off and you'll see it gleam. As far as how long it takes, basically the longer you polish the shinier it gets.
I would avoid using a grinder etc as you're more inclinde to dig in, and you'll end up with an uneven finish, which you WILL notice after you've stood back to admire it!
This is the stuff I mean:
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T25 Westfalia 2.0l Aircooled 1980 in a nice beige colour with a bit of antique steel thrown in