DCA is basically inside Washington DC, so allow plenty of time to get to/fro. DCA is much more convenient than Dulles, which is in Virginia about 45+ minutes from city center.
Try not to fly out of dca during hot temperature days the A/c is broke. And watch out for rats and roaches. I have a friend who works there. She says they have pest problem. I wouldn't eat at the dca.
If u have medical equipment/first aid bag it doesn't count toward your 2 carryon items & u don't have to check it... Sunscreen doesn't count as first aid though...