Long Plane Ride With Newborn

My husband and I will be going on a 15.5 hour nonstop plane ride soon and our daughter will be 3 months then. What advice does anyone have who's taken a long plane ride with a young baby? We booked seats that have a bassinet infront of them. We will also be taking a 5 hour car ride from the airport. Do you check your car seat where you check your luggage or can you take it through with the stroller and check it at the gate? Or should we baby wear and check the car seat/pram with our luggage? Thanks!