I have parked at the Buzz Lightyear lot a couple of times, and yes, it is south of Katella, next to the Strawberry Fields. It does have Buzz Lightyear signage.
This is the last lot that Disney will open, as they need to provide bus service to the park. They contract out to Coach USA (the folks who run the ART system and the Disneyland Express Airport Bus). Since it costs a lot to pay for the bus service, Disney doesn't use it very much. They have an arrangement with the Convention Center to use each other lots, depending on what events are going on. Many times, Disney will use the Convention Center lots when they can (since they can tell guests to cross the street to Timon to catch a tram), and the Convention Center has used the Simba lot and Buzz Lightyear when they have large events.
My guess, Disney uses Buzz Lightyear about 5 days a year.
This is where the Third Park will be built. If you look at the second map, you will see the Mobile Home Parks that are in the news due to the rezoning issue, as you can see, they are right across the street from the property Disney owns.