Reheated breast milk?

My partner would also like to feed our baby but I have a few questions...

Should I pump full bottles, put in bags to freeze, defrost in the fridge then only heat up a small amount and keep the rest in the fridge?

Can you reheat breast milk if I heat up too much?

How much milk should I keep defrosted in the fridge ready for night feeds?

How long does breast milk last once defrosted in the fridge?

How long can you freeze breast milk for?

Sorry for all the questions, I'm a FTM and hardly had chance to speak to my midwife 😭