Sounds like you have things cover pretty well for the plane Corrine! Maybe some snacks (remeber the liquid/gel regulations for carry on luggage) Ear plugs, gum and lollipops...things to help their ears pop if they have issues...
Best thing to do is prepare them for what they will go through...like going through security...having to take shoes off...maybe have them all wear socks...even with sandels if they are squeamish about those things. That tehy will have to go through the metal detector by them selves. Remind them that the plane may be loud and bumpy especially when it takes off and lands...and that it is importatnt that they stay buckled in their seat while the plan is moving!

All basic things to frequent flyers, but just talk to the kids so that they know what to expect. Is your brother not going with you now? I hope he still is, so that you have some help. Especially since the seats are usually only three per side.
Have FUN!!!!!
Lynn