4. heh. I dunno. I guess freezer storage bags would work best. I didn't see a specification.

5. And I guess when they get freezer burnt? We had a years supply of mice in a freezer once, started getting funky around month 9-10; That's with the freezer being left open a couple times paired with power outages. So we now only keep 6-9 months worth of mice at a time.