The seats are an average of about 17" across. If anyone doesn't fit with the armrest down, they can make you buy another seat. You cannot say, "Well, my kid has an extra three inches that I'll use." (First class seats are bigger.)
Many airlines charge you a per-suitcase fee that is not included in your ticket. The suitcases have weight limits, usually 50 pounds. (First class bags are generally free)
You can't take liquids in 20 oz bottles through security, but you can take them on the plane if you buy them in an airport gift shop or whatever. There are rules about how many ounces of shampoo (I think it is 3) you can take. All your little 3oz bottles have to fit into a sandwich bag. I just pack all my liquid crap.
Usually, you get two pieces of carry-on per person. If you have a purse, that's one! The kids get two, too.
Most airplanes have TVs in the seats now, I think. I don't know if they charge a fee for the headphones in coach or not. My sister recently flew on a plane that didn't have the TVs in the coach section, so I guess they don't all, but I think most do.
I'd let the boys bring their little handheld video games (don't know what the popular one is now), iPods if they have them and anything that will keep them occupied. If you give one the window seat on the way down and one the window seat on the way back, everyone wins.
I always put extra cream on my arms and legs because flying dries me out. I try to drink as much water (not pop or juice) as humanly possible, too.
I'm always one of, if not THE last person on the plane and one of (if not THE) first people off the plane. They'll let you board early if you have kids...but if the boys can just get on and sit down without banging other people's seats, get on the plane last. I never understand why everyone wants to get on as soon as possible. You're going to be sitting in that seat for hours!
Every airline will have detailed info about what they charge per bag. The TSA has a website about what you can and can't take through security.
If you buy stuff at WDW that you don't have room to fly home, have them ship it. If you do this while purchasing, they skip the tax, so the cost is roughly the same. In this way, you don't have to worry about fitting stuff into your suitcase or carry-on.
I don't know anything about DME. Sorry.
Have a great flight!
My hubby and I haven't flown since 1997 for our honeymoon to Hawaii, so that was pre 9-11!
