Read some posts, this has been covered, but I'll sum up briefly a little here on the power supply:
It's a 45 watt supply. I have spliced a HD connector into it and it works very well. Other have reported powering both a HD and a CD drive with success. It should most definitely handle a HD and a fan.
The DOC is only useful (and yes, it is) if you're not going to use a HD, IMHO. Some have managed to squeeze an emulator and ROMs onto it, others Linux images, and still others Win95a images. I wouldn't worry about it myself, since you're using a big ass disk anyhow. Getting the disk to boot is the only trick, and that's detailed well enough here on the board.
(Of course, I'm having strange installation problems with Win98SE, but since you're using Linux of some flavor this really isn't interesting - people have gotten both 98SE and Linux to run off the disk just fine on the WS).