The second USB connector was plugged in a separate bus yes? (They can't be connected next to each other, otherwise they're drawing power from the same bus, least that's my understanding.) I've got an USB enclosure for a 2.5" IDE drive and have had to do some trial and error until I found the right configuration.
I did networking when I installed Mac OS 8.1 on my 5300c, using my PowerMac 6100 as the host for the CD and booting from a floppy disk. Sadly it doesn't look like you have any Macs that have the printer/modem port and a CD drive.
I think the cheapest solution would be to use a 3.5" to 2.5" IDE adapter and use an emulator such as Basilisk II or SheepShaver to install Mac OS directly onto the drive. I've booted up SCSI drives using a SCSI PCI card on Basilisk II. You just need to read the documentation and edit the config file manually to point to the actual drive. (Looks something like "\Device\Harddisk0\Partition0" under Windows. You can find the disk and partition info in Computer Manager under Disk Management.)
I did networking when I installed Mac OS 8.1 on my 5300c, using my PowerMac 6100 as the host for the CD and booting from a floppy disk. Sadly it doesn't look like you have any Macs that have the printer/modem port and a CD drive.
I think the cheapest solution would be to use a 3.5" to 2.5" IDE adapter and use an emulator such as Basilisk II or SheepShaver to install Mac OS directly onto the drive. I've booted up SCSI drives using a SCSI PCI card on Basilisk II. You just need to read the documentation and edit the config file manually to point to the actual drive. (Looks something like "\Device\Harddisk0\Partition0" under Windows. You can find the disk and partition info in Computer Manager under Disk Management.)