Every pregnancy is different, so you might want to check with your doctor- but when I was about 30 weeks I moved from CO to PA- so about 1500 miles in the car and that was ok. I did stop and take walks often. Flying is a bit different as the airlines have policies, so I would check on that with your doctor and the airlines.
You can always call and check with your doctor.
Yes. If by car it's recommended you stop and walk for 15 minutes every 2 hours. A plane is generally considered safe untill your last month.