Newborn caregiving questions

Hi mummies, I have some questions if the community can share your experiences and advices pls! My bb is currently 5weeks old 1)How do I gauge the amount of milk I should feed him? Accord to research he Shld be taking 100-120ml. But he kept spitting out milk and having difficulty to burp though we tried many methods of burping/ helping him to release gas e.g. bicycle stretches 2) it seems like my bb has alot of gas, not sure why. Any better methods of releasing gas? We tried applying Ru Yi oil, added Riwind Med into his milk .. 3) he seems to sleep very well during day time but not so wee hours onwards. Anyone experienced this too? Can share advices pls? Thank you all in advance!