Re: long car trip and nursing?
We did a 16 hour drive (in 2 days) with our DD when she was 3 1/2 months old. We scheduled time to stop along the way, such as stopping at a restraunt and spending time, relaxing, nursing, and just changing the diaper. Believe it or not, it turned out to be a more pleasant trip, because we did plan stops to nurse and such.
She did sleep a lot, but we still stopped to nurse (Even when we thought she wouldn't wake up) she still nursed in her sleep. If it is planned, you should have an easy going trip.
Oh, we also planned gas fill up, eatting, nursing, changing and our using the restroom all in the same stop so it worked out great.