You can carry 3 of cream onboard with you unquestioned. Or multiple 3oz containers.
Hubby traveled a few weeks ago and had a 12oz Jergens bottle in his pants pocket, which he forgot about. It went through security unquestioned, although he did have to pitch one on an earlier trip.
If water is an issue, I'd suggest getting a doctor's prescription for your special needs and carry it with you. Otherwise, you can let the airline attendants know upfront that you will need water more than average due to medical needs.
I don't know anything about the Atlanta area except for the conference last year. It is very mild this time of year - sort of like a spring or fall day in more northern areas.
When you rent a carseat in a rental car, don't be shocked if it is a total piece of s***. I made that mistake once, and have travelled with my own carseats ever since. Yes, they are forward-facing only, so only good if your child is over a year. The car rental place will not install it for you - they make you do it yourself so they aren't liable if something happens. And they don't install well. The cars are usually new and have LATCH hooks, but the carseats, in my experience, are usually older and the cheapest ones on the market.
Ichthyosis-en-Confetti Type 2
Husband, Nathan - 10, Elliot - 7, Oliver - 4, all affected.
I also have an unaffected daughter, age 8.
email: jennifer at confettiskin dot com
facebook - find me on "ichthyosis mommy spot" or "friends of ichthyosis"