You'll need to locate the OBDII port which is under the footwell near the dead pedal. But first, update the AP on your computer with the latest firmware. Then, just plug it into the OBDII port and put the ignition to 'On' and the AP should fire up and you can then choose to install the 91 map. It's a snap.
Yes, if you want to put it in valet mode you'll need to reflash to that map and have the AP on you. Changing maps takes no time at all.
Definitely run the 91 map for our 92octane gas here in Washington. I was running the Stage1 map for about 8 months but decided to get an e-tune from BrenTuning. It's made a world of a difference in the car and is lights out better than the Cobb OTS maps. Hope this helps!