Some good advise on these sites. I have always tried to live by the old adage :" Take along what you are comfortable with".
As for camera bags, they are great for storing things and a pain to travel with! I use a trout fishing bag, made by Brady in UK. It does not look like a camera bag, it has two smallish outside pockets for my pipe/tobacco and matches and the second one holds whatever paraphenalia that I think could be useful that day. The inside is unpadded (has a rubberized snap in lining - designed to carry a live trout home !
I am a devotee to the two bodies/3 lens package. One body, usually with a 35 is around my neck or in my hand. A second body in the bag with either a 50 or a wide (15/21/25). Third lens is wrapped in a piece of cloth and can be either a super-wide or a faster lens, occasionally a 75 or 90.
As for film - I dont experiment on trips! Air-fares and hotels are expensive enough as it is, without having to contend with unknown entities like films. It is TriX all the way. I throw away the boxes and plastic cans (usually keep one for spare batteries) and stick the film in small freezer bags (8-10 rolls per bag). I usually count on 4-5 rolls per day (2-3 rolls/camera). Every morning I restock one of these bags and it goes into the left pocket of my vest. As the day progresses I put exposed film in the right pocket. Pick -pockets abhor photovests - there are way too many pockets and usually noisy velcro tabs to contend with.
I sometimes stick film containers back to back and tape them together with gaffers tape (use 24-30 inches of it). This means that you can tear off a small piece and write notes on it and stick on the cassette. Tri X pushed to 1600 looks the same in the cassette!
If it is a long trip or a camera behaves strange - I buy a roll of cheap color film, 24 exp, and run it through the camera. If you check the speeds, run it so that the setting and subject is the same across the board. Then have the roll processed at a 1-hour lab. The prints should look the same, only the DOF would change. Much better way than coming home and finding out that the shutter has been capping for the last 30 rolls ( been there and done that!).