So, just for reference of anyone looking through this thread later or anyone looking in the near future, the Graco Magnum Project Painter Plus Paint Sprayer worked very well. Had no problems with it.
Dirty was able to paint about 3000 square feet in just under 3 hours. It took about a half hour each time to clean the gun afterwards. He was spraying directly out of the 5 gallon pails. The primer was oil based Zin Stain Cover. It covered the markings on the plywood. The knots in the plywood, not as well. You can still see the darkness in some of them. The paint was American Heartland exterior barn paint.
There was plenty of over spray the 3 foot rosin paper we put down caught most of it. Looks like we have a little floor scrubbing to do.
The progress continues. Funny how you get motivated when you can see real progress and not just doing mundane things like hanging 90 sheets of plywood. Put up the first section of wall. Also connected the second section to it. Dirty's been putting the joists on for the mezzanine floor. He had enough done to throw a sheet of plywood up there. I thought he was going to take a nap.
Went and got $1500 worth of lumber to finish the rough in and the floor. Holy crap is the price of wood up!
Top of the plywood is 8 foot. Added a 2X10 header to the 2x6 stud wall to give the mezzanine more strength. The mezzanine is only 8 foot wide.