JB,
We took our 7 1/2 month to Florida (Tampa). And he is not very good at Sleeping in our arms as well. He is more used to sleeping in his crib. We very rarley get him to sleep by holding him. We did not purchase a seat for him all we did was hold him. Going there he slept except for the first 5-10 minutes until we were on the ground in FL. Coming home he slept about 1/2 the flight and played with the bags of snacks that we got from the airlines. He did very well.
For medicine, they will allow you to bring what you need in a little cooler. We flew Southwest and they allow 1 larger caryon and one personal caryon like a purse or small cooler per ticketed pasenger. We got 2 checked bags per ticket, so we could do 4 checked bags. The stoller does not count as a checked bag, it is like a wheelchair. We brough the Car seat/stroller combo.
Going through security we were allowed to bring as much milk/formula as we needed. Since I am nursing I had two bottles that I froze and put them in as the "ice pack" and then a few other bottles. Definetly have a bottle for him for take off and possibly landing. Also if he takes a pacifier have them handy as well. They did not question me as to how much I was brining or anything like that.
Traveling was not as challenging as one would think it would be with the baby. We brought the front baby carrier (Bojorne is the one we had) for walking thorugh the airport as well as had is srtoller. We put him in the carrier to go through the metal detector which was easier than just holding him.
Good luck and have an enjoyable trip.