I'm not sure about the baby food. I don't think you can. You can take a sippy cup with milk or juice it in (I was told this on Sunday when I flew with my baby) but I would think that baby food might be out of the question.
With regards to drinks for your older kids, I know that's an absolute no. Depending on your flight, they may give you drinks once you get into the air.
We flew at 5:30 a.m. both to and from FL and I packed Clif bars for the kids. They are energy bars and they even make kid Clif bars (Target sells them in the Energy Bar isle - in the Pharmacy section). They have a lot of fiber and protein so my kids ate those and weren't hungry until we could get somewhere to feed them a real breakfast/brunch.
We always take things to entertain the kids (books, coloring books and crayons, mp3 player, dolls, etc.). That makes the ride go a lot smoother and any time that you get stuck in an airport when flights get delayed and/or cancelled.
Good luck!