I don't know about the first question,
but you could still make backups on that other drive, as long as you only copy files and not programs across.
As for the Master and Slave thing, connect them up in that order. If the Master had Windows on it, the Slave wouldn't need Windows, but if it does as well, windows will ask which one do you want to boot from, and just choose the one with the files on.
Then just start dragging files off from the Master to the Slave
I hope this helps, and welcome