The Legend, you're welcome. I'll try to answer some of your questions by giving you a few of my own Grand Plan vacation experiences.
I have Grand Planned twice at the Grand Floridian Resort & Spa. My very first WDW vacation was at the Grand Floridian Resort, in a concierge room located in the main building. I added the Grand Plan package on top of that specific room. Since I had a concierge room booked, of course I had access to the concierge lounge. My next WDW vacation was in a two-bedroom suite at the Grand Floridian. I added the Grand Plan package on top of it. Disney gave me a suite in Conch Key, even though I had requested one in the main building. Of course once I set foot in my suite, the Cinderella's Castle view brought tears to my eyes and I was so thankful that they gave me that suite in Conch Key (Conch Key has long since become my favorite Grand Floridian building). Anyhow, since that suite was not located in the main building, they told me over & over again that I would not have concierge access. I thought that was rather petty since I was spending several thousand dollars a night for my suite & the Grand Plan (I had my sister's family vacationing with my family). However, there was nothing I could do to change the Grand Plan folks' minds. Fast forward to my next Grand Floridian two-bedroom suite stay. Of course I immediately requested Conch Key. This time I had my sister's family vacationing with us again, and my parents were also supposed to vacation with us. Since there would be such a large crowd, I decided not to add the Grand Plan to that vacation (it would have been a complete waste since my parents wouldn't have used it at all except for a few meals here & there). Well, surprise, surprise, the Grand Floridian folks told me that since I was in a suite, I would have access to both of the Grand Floridian's concierge lounges -- the main building lounge and the Sugar Loaf Key lounge. How funny! The prior suite stay with a Grand Plan gave me no concierge lounge access, but this suite stay without a Grand Plan gave me complete concierge lounge access. So, as you can see, anything is possible with Disney. And anything is subject to change at any time without prior notice.
I had a Grand Floridian Grand Plan booked initially for last year, however, I had to cancel it due to the fact that my parents & my sister's family unexpectedly invited themselves along on my family's vacation. When I was planning the Grand Plan, I was told that I would have concierge lounge access no matter where my room was located. I do have another Grand Plan vacation planned for the Grand Floridian, but I am not sure if that still holds true since I have not been contacted by the Grand Plan folks yet. At this point I have no expectations since Disney always seems to have a way of surprising me.
By the way, the Grand Plan may only be added on to vacations at selected Disney Deluxe or Home-Away-From-Home resorts. The Deluxe resorts currently allowing the Grand Plan vacation package are the Animal Kingdom Lodge, the Beach Club, the BoardWalk Inn, the Contemporary Resort, the Grand Floridian Resort, the Polynesian Resort, and the Yacht Club. I would like to note that the Wilderness Lodge does not currently allow a Grand Plan vacation package, but I do know that in the past it has, and thus will probably allow it again in the future. The only Home-Away-From-Home resort that currently allows the Grand Plan vacation package is the BoardWalk Villas. (I verified all those resorts by looking at the WDW reservation website.)