According to the hotel website transportation section:

http://www.marriott.com/hotels/maps/...arriott-hotel/

, the bus stops at Krankenhaus (Hospital), which is .1mile away from the property. Two pick-ups at airport according to this, which also has timetable.

http://www.mvv-muenchen.de/en/home/index.html

Given you're getting in at 6:30pm you might want to consider taking the train from the airport to CY City Center, and have a nice meal/stroll in the city & then train it back in the morning.

But if you do stay at airport, supposedly central Freising is only a few minute walk from the hotel so there might be options there. The hotel doesn't have an executive lounge, but you'll get a full breakfast in the morning.

Cheers.