honestly the younger they are the easier it is to fly/travel with them
Ive travelled a fair bit with my two.

yep - feed on takeoff/landing for sure, more than likely she'll sleep for you

Id wrap the seat in a garbage bag - you dont want it getting wet. Ive taken seats before and theyve been fine. Much easier having a car than having to taxi everywhere! (Ive done both!)

Thats all I can think of atm. Hope all goes well