Definitely do the park and ride. Parking near the mall is a headache. There are about a dozen lots at least. We've always used the one at 94 and Snelling.
Also, if possible, go see a live birth exhibit in the animal buildings. You can see cows and pigs deliver. Maybe that appeals to you -- maybe not. Just eat after you go. Ha.
I think foodwise, the one absolute must is the roasted corn. You'll see hundreds of people walking around with one. They're unbelievable. I know it sounds boring, but this is the upper midwest. We perfected corn. There is one stand. See a map put out by the fair or the Star Tribune.
Otherwise, ferris wheel ride at dusk.
And keep in mind, the massive crowd is both good (people-watching!!) and bad (can't move -- AHH) and Sundays are the most crowded days. If you want freer movement, consider a weekday, getting there at a time of day that will allow you to be there at dusk on the MIdway, when the lights come on the rides. It's a great time to be at the fair.