Traveling tips with a 6 month old

Ok ladies so I’ll be flying from Seattle to Nashville with my 6 month old baby girl on Friday I need some tips/advice. So I’ll be visiting family and staying for two weeks should I take all three (stroller, car seat, and base)? Or should I be ok without the base? Should I purchase a bag for the car seat and stroller to help from scuffing? I’ll have a 40 mins layover in St. Louis so should I check in and check out the stroller at the gate there? Also she’s going to be a lap child so should I try to board first or wait and board last so she won’t get fussy waiting? Sorry if it’s too much this is my first time flying alone with a baby. TIA