There are such things for SEP called "Home Use," licenses. If your organization has 1000 computers, you buy 1000 licenses of SEP. And you can then purchase up to 1000 home use licenses at a largely discounted rate.
Basically you can buy as many home use licenses as you have corporate licenses.
As for your other question, I wonder if you can export the policy in the SEPM, and import it into the unmanaged client. It's manual, but easier than what settings need to change from the default.
You may have to export the unmanaged settings, and export the managed settings, and copy and paste lines into the XML to make it work?