1. No, you didn't miss it. I didn't mention it anywhere except in the PDF download, I think. What I used was some small brackets attached to the rear edge of the control panel. I believe the brackets are some kind of mirror hanging clip. I pulled them out of drawer at Home Depot in the hardware aisle. I'm not sure how well this pic will show them, but it will give you an idea.

I had also planned on attaching the top edge of the plexi with an aluminum angle or Happ marquee retainer, but the weight of the 1/4" plexi was enough to keep it in place without supporting it on the top edge. I cut the plexi for a snug fit between the cabinet sides, too, so that helps keep it tightly in place.
2. I printed out the graphics on Avery full sheet labels, then cut them out and stuck them down. I didn't use any type of laquer, just places the plexi directly over them. The cabinet is a year old now, and they look just as good today as the day I printed them.
3. No problem!