The MOA is about a 13 minute ride from Terminal 1. At MOA, it will drop you at the lower transportation level. Follow the crowds up one level to the entrance of the Mall, where you will find a customer service desk, as well as small storage lockers. Make sure you pick up a map at the desk.

If you want a quiet, peaceful place to eat, without the noise and commotion of the Mall, I suggest the Cafe at Nordstrom. The food is very good, there is Wi-Fi, and the environment is very relaxing. I believe it's on level 3 of the store.

Two good resources:

http://www.mallofamerica.com/
http://www.metrotransit.org/metro-blue-line

Though the actual ride back to MSP will not take long, allow enough time, as the jaunt from the the Terminal 1 station to your gate will take some time.

Hope you enjoy your excursion.

BTW, MN has no sales tax on clothing.