Can do either. I used to just do it for 20 seconds in microwave with the lid off and swirl it. Now he prefers it cold anyway which helps haha.
Yes, i use mam bottles too. I microwave cows milk for 1 minute with the lid off x
I would test if he will take it cold first
Just get the easy active ones ones and leave the lid off that’s what I used to do. About min 10 for 8/9oz x