Nope don't do cares. You baby is to light and small. Take the keyfit. You might need to ask the FA for a seat belt extender.
You can bring any foods or drink for a baby/toddler. I recommend two days worth in case you have a delay. When you go through security just declare your stuff and they will tell you what they want done with it. Milk, breast milk, food pouches, water, formula, juices, etc are allowed. You are also not subject to size restrictions.