I'm going to be adding a second hard drive (and yes, more memory too

) to a standard configuration QS PowerMac, manufactured in 2001. It has a 40GB 7200 rpm hard drive in the lower rear carrier, and a cdrw in the upper bay. I see that there are extra connections for power and drive at both locations... supporting another ATA at each location. From looking at the documentation I've found online, it looks ok to add at either, as 'slave". I intend to install OS-X on the new drive, allowing the owner of this QS to boot both 9.2 and Tiger (she wants to finally make the migration, but slowly...)
So...my questions:
1. Can I add the new drive to either location? (as slave?)
2. There don't appear to be size limitations to the hard drive, that I can find... are there?
3. Are there any other gotcha's to watch out for with this model?
Thanks!