Bring some toys that baby usually plays at home but if it’s a 1.5hr, try to let baby stay awake and then sleep before boarding.
You can use pacifier instead of feeding its fine.
Yes you can, you’ll definitely get stares if baby cries but just ignore them.
It depends on your baby, if baby normally sleeps well in carrier then use the baby wear, when sitting down, konny will be better and more comfortable for you compared to ergo. If you’re worried about the pressure in ears can consider ear muffs (not sure if 3.5m got suitable ear plugs).
If everything above doesn’t works and you still have a crying baby……screen time or play music.