Mike, nice picture and drawing
1. Nope. There are no wall studs in the headboard wall. In my link there is a picture of me holding a stud finder looking for a wall stud. None there. I drove fat screws at alternating 45⁰ angles to help prevent them pulling out.
2. Colorados idea of Using L brackets to anchor the sideboard to the moving floor is a good idea. Use short screws to prevent them going all the way through the bottom.
3. When you remove the plywood floor of the bed you will see the hollow cavity (picture #5) between the inside and outside wall. The entire bed frame is made of 1x2" with 1/4" Luan stapled over it. That's why I cut and fit more 1x2" and slid them into the cavity and drove screws through them. Same with the 4" screws anchoring the bed wheel 2x4 board. They go through the additional 1x2s I added.
4. L brackets anchoring the sideboard to the moving floor is a good idea.
5. In the picture, the bed is extended away from the hole in the floor the wiring is coming through. The wheels running over the wires is not an issue.