What did I learn, take home points.
1. GIK makes good panels. There are 4 hooks already preset in the rear of the 242 panels, they are actually identically located on all the panels. Makes for easier and more uniform cloud hanging.
2. You need a strong drywall hanger, I found the toggle bolts to be great. I think 2 is enough to hold up a 242, 4 is overkill.... but that's what I like, overkill.
3. Definitely need the washers to not only cover up the hole and make the clouds look more professional, but to also align the hooks on the vertical plane to each other... otherwise, if you think about it, it's hard to vertically match all hooks when there is no "stop point" as you are screwing the hooks into the ceiling.
4. Measure 3x, drill once. I don't think this step can be overstated. Preplanning is key.
5. It took me 4 months to preplan because I was not sure how to attack the installation, once I figured out how to hang the panels, it was then a matter of how to demarcate the ceiling for install locations/drill spots... the actual installation was the easiest... just drill and install the hooks.
6. The drilling - you need to start with a small drill bit so as to align the holes better, then gradually drill bigger and bigger holes. The final hole is 5/8".
All in all, it was a fun project and I'm very proud of my handiwork.