Connect it to your PC or laptop and do a netinstall. Configure SSHD and a static ip. Plugin the disk to your server and then connect via ssh to admin it.
You could also set your laptop or PC to boot from the attached disk in the bios to test the services you want to start are starting
Personally I just throw my roms in directories and serve them from nginx. Its easier to just pull them down on deck that way and requires no extra effort or maintenance on my end.
Everything else is on steam.