I'm very close to the wiring stage of my control panel

and have a couple questions that I didn't see specifically answered in searching the board. Here goes-
My CP box is 15" x 47" so there is plenty of room. I am mounting an IPAC4 and the new Druin board (very small). I have 2 sets of PCB mounting feet already purchased.
1. I was planning on mounting both boards to the floor of the CP box. Sound okay?
2. Is there a recommended distance I should place between the two boards, or should I just place them as far from the controls above as possible?
3. This is my first wiring job. Would things be easier for me if I mounted the boards first, then attached wires, or should I attach everything and THEN mount the boards to the feet?
4. As far as the PCB mounting feet themselves, am I correct that I "sandwich" the board betwen the foot and the long plastic piece that keeps the bolt from going very deep? I know I didn't explain that very well, but my guess is that if you know the answer, you get me.

Thanks.
