Majority of the data (video) is already compressed as MPEG-2 so I’d think it doesn’t compress very well. But if you don’t have enough storage it’s always an option to re-encode video with something more modern and achieve smaller file sizes from that. But that also removes at least DVD menu and other ‘format dependent’ options.

That would get you an exact copy of the disk with everything on it. And also, while 200 DVDs sounded a lot, it’s “only” 860GB (assuming 4,3GB/disk which I think is the most common for movies), so it’s not stupidly expensive either. Obviously you’ll want a RAID setup and most likely backups for that, so it’s more than just a single 1TB drive, but still quite manageable.

Ah, you’re correct. I somehow misunderstood the assignment, OEM installation is a bit different and I don’t think there’s a Debian version of that readily available. You could of course write scripts to manage that, but that’s a quite a bit more difficult than just set up preseed for the installer. Or you could just include instructions on how to set up your accounts afterwards, but that’s not the same either.

Debian (and I suppose a lot of derivatives) can use preseeding. That gives you pretty much full control to the whole installer where you can just start the installer and it does everything for you, including users, partitioning, installed software and so on.