17mm is too tall: it'll just fit, but there's no room for the drives to vibrate in the shock mountings.

Partitions: for a second drive and the maximum space, partition it as *all* hdc4 (well, 4th partition as the only partition) then mke2fs it from the developer image. A "genuine" drive has 32m, 32m, 16m, then "rest of disk" as the 4 partitions, all linux ext2fs type (0x83?) - you'll need this if you're replacing the primary disk: with this format, upgrade files will apply to the new disk cleanly, so you can apply developer then exit to shell and mke2fs the new hda4 partition.

When mke2fs'ing, use -m 0 to reserve 0% for the superuser, as this isn't really needed :)

Hugo