Data files: Look into the "SAMBA" server with RH9. That's the open source version of windows file/printer sharing (much more too, but it's bread and butter is printer/file)
USB Printer, won't be a problem at all. RH9 knows about an assload of printers, sees my HP just fine. Same with the scanner.
DVD: Good luck. DVD Movies have that lovely copy protection on them. There might be a player available now, I haven't looked in awhile. DVD data, not a problem at all.
I suggest if you stick with RH9, go out and buy a book on RH9. Something from the "Unleashed" line, or "Teach Yourself RH9." It will have the printer/scanner stuff, plus Samba, and maybe even the DVD stuff.
edit: RedHat Linux 9 Bible
looks like a good book for the subject.