for security check, can we take formula and formula water through security check or does the formula need to be remade - which will get spoiled if not kept refrigerated.
No, you can bring formula, water for formula and powder. No restrictions. Any liquids meant for a baby are allowed in "reasonable quantities" but even amounts for long haul international trips aren't questioned. Basically, anything related to formula is good.
we bought a seat for our baby as well and I plan on taking the chico keyfit30 carseat for the plane, is it easy to install without the base?
Should be. Practice in the car before you fly. You can't use the base on board. I recommend just leaving it at home and making sure you can do the seat belt installation comfortably. Just one more thing to lug around!
Check your manual where instructions on the seat belt-only installation and airplane use instructions are. Make sure your FAA sticker is readable.
Kudos for buying a ticket for your baby!
also taking the uppababy stroller, can we gate check the stroller?
Check your airlines' website but that should be fine. The only airline with a restriction is the 20lb limit on AA. I think the Uppababy should be under that anyway.
If you reach the airport a little early can is there a possibility of an upgrade?
Really can't tell you. What airline? Are you a ff? You might want to ask this on your airline's board to get a more accurate answer. If it's Southwest, the answer is no (only one class of service!)
Flying tips in my siggie below.