Thanks for the advice....I was thinking of going from stroller to carrier back to stroller, as we progress from the car, through TSA, and finally to the boarding area, simply to limit the amount of time my wife has to carry baby (as she's gotten quite heavy...the baby that is). She typically does the baby carrying so that I can deal with all the car seat acrobatics, lift heavy objects, and leap into action for whatever. But I see the benefit of keeping baby in carrier from start to finish in order to limit disruption to her. We purchased a seat for baby so will be boarding with the car seat for her to sit in, but will definitely be gate checking the stroller.
To answer the other question re: baby supplies, food wise we'll bring some food for her such as those puree pouches, but she can also eat solids/reg food so she'll get that too. We're staying at the BWPPI which is "the one in front of the crosswalk" right across from the DL entrance so that limits our choices of where to buy things without a good walk involved. However, in a pinch while at the park we plan on going to the baby center for things like diapers and so on.