BMilk Storage and defrosting

Hi! I have a few questions I'd love some insight on, how do you store and devide your breastmilk in feezer? So far ive just been deviding per what i pump as i am only pumping once a day and freezing and solely breastfeeding, with one bottle feed a week ish from husband, so it varies between 2 oz and 6oz in feeze bags, as km not quite sure how much he eats either

2. If he eats more than my 2 oz bag(which he does im sure) can i defrost another 2 oz from another day and place in same bottle? Or do i have to do 2 different bottles in one feeding session?

3. Can i defrost a bag of milk in my munchkin bottle warmer?(as it has bottle lift and doesnt touch the heater directly?

4. I feel like i had many more questions so i will probably be back qith another post on few days hahaha

Thank you ahead! Like i said ANY imput on how your regulate would be nice and appreciated :)