As to the shelf, that actually came off the wall. The guy who had the house before me and used this workspace had it setup in a way that really confused me. He just had a big piece of plywood for a backwall and just hammered nails up for hooks. In fact, all the projects in my house done by this guy used nails instead of screws. That shelf was hung up by driving nails above and below the back bar to hold it up.

Oh, and then he painted the whole thing white. Back wall and nails. It was like walking across the north pole. I had no depth perception in the shop. The nails were invisible. I spent a weekend ripping all the nails out (including that shelf) and putting up the oh-so-controversial peg board.

As for the orange speed square: I love it. I use it as a circ saw guide all the time.