I believe it's worded as such due to the fact that you reserved a premium, so you will be able to take from the designated "premium" section (assuming it's even in use). If you had a midsize reservation it would say something to the tune of "Upon arrival, proceed to the Emerald Aisle and choose your vehicle" etc.

To answer your previous question: that was just a list of upgrades that I've gotten. Those were divided between MSP and GEG over the course of a couple years. I don't rent frequently, but National has been dynamite on the upgrades for me.