Hi J.! I agree with other Moms about bringing the umbrella stroller whether he rides or not, it can help tote other items. I used to bring several bunji cords of different sizes and strap the carseat to the stroller and then put my carry on in the carseat. Of course, this is assuming your son is walking, not riding....which, unless you are rushed, I highly recommend because it helps him burn off energy and the excitement level will be high whether positive or negative.
We always got books about flying from the library a few weeks before a trip to plant the "this will be fun" seed and hopefully allay fears. don't forget to bring something for his ears whether he still takes a bottle periodically or uses a sippy or straw cup....you will probably need something to help him swallow....one of my daughters was never bothered at all though, so you never know.
The last suggestion I have is to get a miniature cow bell (they sell them at Walmart for a few dollars for a 2 pack) They are really fishing pole bells to put at the end of a rod and will jingle at the slightest movement. The bell is not so loud that it is obnoxious to other people but the pitch is such that you can hear it easily above the other sounds in the airport and not only does it let you know he's on the go, it also lets other people know he's around so he doesn't get crushed. My kids have a blast just jumping, wiggling and singing to the bell (I clip it to their backs at a right angle) so it can be a fun "waiting activity" while stationary too! If you can't find the bells at a store near you, look them up on eBay....I know they're sold there. If the cost is too high, let me know and I'll list a set for you for a couple of dollars and ship them free.....I'll be selling some with my summer toddler kits and I have a dozen + clipped to the curtain in my kitchen! We use them outside at home, grocery shopping, the mall, you name it, we probably use them there...the bells are the first thing their friends ask for when they come over to play! Hope this helps a little....have fun! M.