Storing in freezer questions

Just a few questions as I begin to store milk. I read on the storage bag box to store them standing up but I've read here, to save space, a few of you store them lying down. I know this is in case of leakage...I lay my bags on top of each other in an open tupperware container.

Anyway, my question IS- when you seal the storage bag- do you squeeze out all the air, or leave some air? I know you are supposed to leave an inch for expansion but I'm not clear if this is an inch of air.

Also, I know the milk stays good for up to 3 months...how should I use it? Should I use this months frozen milk next month while I use next months fresh milk to store? How do you guys use your frozen milk?

TIA