The class of service is irrelevant. Those of you who think that babies should not be in F show a bit too much superiority for me. Babies and people who behave poorly should not be in ANY class of service. No one likes a screaming baby, but it doesn't matter if it's in first or coach -- sometimes babies cry. And sometimes people get way too drunk on airlines, particularly with the free-flowing scotch in F.
Regarding changing babies -- I feel that it is the airline's responsibility to provide an appropriate place for this. If the restrooms allow for this, great. If the restrooms are too small, make one BIGGER for this purpose. Changing a diaper in the passenger seating area is not appropriate -- the airline needs to deal with this and make an appropriate place for this. (No, the drink trolly is NOT an appropriate place.)
Breast feeding? Breast feeding is fair game anywhere. GET OVER IT and if it makes you uptight, look the other way.