Disk 1 = 750 7200rpm (C boot, system, primary partition. I'm thinking of adding a SSD as a boot drive with a fresh install and a 2TB green. Here's my question. How does Disk 0, Disk 1, etc. matter ...

I have two SATA disks, disk 0 has the OS on it, disk 1 is empty. I can add disk 1 to a storage pool , but that's not going to help.