Note to self: Never wander away from SimV for more than a couple days, or you will be replying to everything in a very belated manner!!! Yeesh!
OKies, Minneapolis-St. Paul Int'l - part of my stomping grounds! Woot! To answer the most pressing of your questions (Is 40 minutes enough time for a transfer?), yes, but only if everything goes as planned. If your first flight is delayed, you could see that 40 minutes evaporate painfully fast. Also, some flights will require (require) that your but be in your seat on the plane with time to spare. Often this is 30 minutes before your flight. Sometimes they will be a stickler about boarding and refuse you permission to board if you are running late, and other times they will let you squeak in. But, you should subtract 30 minutes from whatever time you have available to get a more correctly adjusted time available. In your case, this means you really have about 10 minutes to get from one plane to the next, and that sounds a bit tight to me.
If you can (i.e. if it isn't too late and works out with your itinerary), I would recommend giving yourself at least an hour's window, and preferably two, to make your connection. KMSP is one beauty of an airport, and should you find yourself having time to spare there are great restaurants, pubs, shops, and the like all within the passenger waiting areas to enjoy. Every time I fly to or from home, I end up going through KMSP and I always enjoy my time there. A bit of time spent at the airport for the sake of a buffer makes up for the possibility of a lot of time spent at the airport because of a missed flight, ne?
As for NWA, I fly them ALL the time, exclusively! Every now and then I run across a crew that seems to have had a bad day, but that is not the norm. Usually they are really great and accommodating. On occasion they even let me up to the cockpit of a 747-400 and into the co-pilot's seat for pictures. That was just simply fantastic service and a surprise treat that I will always cherish. As for your luggage, if it is a domestic flight, they should make all the luggage transfers for you automatically (just don't forget your carry-on's!).
I hope you have a great trip, and I would love to hear how things go for you flying NWA (specific interest of mine).
All the best,
Darrin