I think it was mostly dubplates (one-off acetate masters straight from the lathe), can't play them very many times but they're fast and cheap, I've definitely heard anecdotes about people finishing a track in the afternoon and having it cut and in the right DJs' hands by that evening. I don't know a ton about it though.

As far as recording, I've seen people who were doing it post on forums about it and it sounds like they usually sequenced everything and then rented a studio to do the mix, moved all their gear down (or did it at home if they didn't have the money for a studio), mixed to steree DAT or videotape and that was that, everything gets set up for the next track, not much worry about repeatability.

Wow. There's a longer one in the related videos at the end. There was an indoor amusement park and everything.

The WATMM thread that reminded me this stuff existed and clued me in on videos of it being hilarious actually had one poster use "Thunderdome" as a label for a particular variety of gabber, so I guess it was one of the epicenters for it.