Sounds like you're spot on with those prey sizes CK. Keep the BP on smalls and weaned rats will be perfect for your BI. I'd thaw one of those old feeders and see how it smells before tossing them. If they've been in the freezer undisturbed for a year, they may still be good. If they pass the smell test, and aren't super squishy or have parts falling off, I'd offer one to the BI just to see how he responds to rats. If you order a new pack of weaned rats they usually have (20) in a bag so one bag will last quite a while if you're feeding bi-weekly.