My son is 2 1/2 now but I took him from Miami to Buenos Aires when he was 4 months, and then Miami to London when he was 10 months old. Yes, bottle or breast feed for take off and landing. When my son was 4 months, I held him most of the way, but he did sleep on his usual schedule. When my son was 10 months, we bought the car seat onboard the plane and bought him a ticket (traveling at holiday time and knew we needed a car seat in London anyways). For 10 months old, I brought formula, my breast pump, baby apple juice and nursery water as well as plenty of finger foods and Gerber jar foods. I had no trouble getting through security in the U.S. but I took enough Gerber for our week in the UK and the way home, and had trouble getting the food through security in Heathrow, coming home. My son has severe food allergies, so I wasn't planning to expose him to anything new. I cried and they let the Gerber onboard that time:)
I agree with the Bjorn/sling for use going through security, in the airport, etc. Strollers are a lot harder overseas, many places don't have elevators, lots of stairs, the ADA doesn't apply outside, so we had a tough time with stroller in both locales. If you have any other specific questions, don't hesitate to ask. Oh, to this day, I take two outfits for my son in his diaper bag, and a compete change of clothes for all of us (my husband when he is with us) in a carry-on bag. I also gate check stroller.
Good luck and enjoy!