Back in the day it was all easy. Because there was only one way to do things, and there was complete documentation and tips for third party vendors who wanted to sell to the Mac crowd. Disk Tools is one of the multi-part install disks on Apple's Site for 6.0.8. The interleave is handled automatically on the SE. Non-Apple approved drives may or may not be recognized properly depending on how they are formatted on other equipment. AppleTalk will likely be the easiest to setup. 6.0.8 is ready to go, as is System 7 on your later Macs. Just plug a serial cable into the SE and directly into the other Mac, set up Apple Talk, and sharing and transfer your files to hearts content.