Hi Dee Sa
The USA doesn't feature in the top 50 countries that I'd like to visit. (I doubt that it would be in my top 100). Additionally US airports have some of the least informative websites anywhere in the world. So I'm certainly no great expert when it comes to questions about the USA!
To some extent the answer to your question will depend upon where you're travelling from, your preferred flight times and (of course) the prices of the flights. If you're in the north of the UK, Continental's flights from Edinburgh or Manchester to Newark might be worth considering. Otherwise you're restricted (for direct flights to Newark) to a choice of Continental, BA or Virgin Atlantic out of Heathrow.
If you're only going for a short trip, you probably don't want the time-consuming hassle of changing flights. The only direct service from the UK to Minneapolis is with Northwest Airlines from Heathrow.
I'm also not the person to ask about shopping. (Even if I had the funds to buy a complete new outfit for myself, I'd only pay for half an hour's parking on a pay and display car park. That would give me plenty of time to go through the absolute agony of shopping and then to have a leisurely coffee afterwards!). However these might help you:
http://www.mallofamerica.com/#/main/home/home
http://www.tripadvisor.com/Attraction_Review-g42881-d109972-Reviews-Mall_of_America-Bloomington_Minnesota.html
http://www.insiderpages.com/b/3666717340
Chris