Kalispell (FCA) is the closest option with only a 30 minute drive. However, if you want a (possibly) cheaper option and more of a scenic drive through Montana, you could fly into Missoula (MSO) which is 1.5 hours away. Bozeman (BZN) is a 4 hour drive, but it's typically the cheapest airport in Montana.

Yes! You can take the train straight to Whitefish and work out a rental car from there.

Yes! Because it's such a vast area with little public transportation, it would be really hard to get around the area without a vehicle. Driving your own vehicle, renting a car, or using Turo are all options. *Note: Because it's such a busy area during the summer, rental cars are often booked early and unavailable; book one sooner rather than later.