Using them with Serato is only with a Serato certified mixer or soundcard I think.
As for learning, it really is pretty straightforward. Just make sure to download the latest RekordBox software and prepare you playlists and tracks there. Then create a USB-stick to take with you (make at least one, but preferably two clones of the stick). If you have two hours to play around with the CDJs before the gig, you should be fine. Maybe you’ll have to forgo some of the advanced tricks on the CDJs, but it’s better to spend some time on the mixer (especially the FX section) too.
Good luck. Let us know how it went.