I'm planning to build a little shelf for behind my couch. The top piece and side piece will be nicer wood, probably stained or painted, don't know which. While the wood frame underneath will be some 2x4s or something.

The other part of the plan will be to eventually drill a hole in the top to put a recessed powerbar. 

So I'm wondering if the 2x4 at the top of the frame needs to go the full length, or if I can leave a gap in it where the recessed bar will eventually go.

So my questions are....

1) How should I attach the wood that is visible? Should I screw from the inside out? So none of the marks can be seen? Or should I just use my brad nailer and go outside in?

2) Do I need more structure on the frame to make it stronger? 

3) Should I cut the visible connection at 45degrees to make it look nice? I have a router, so I could smooth out the edge. Or would it be easier to just connect it similarly to how I crudely drew it, and then router the one piece that's sitting on top?

One other thing I need to consider is that I want it to be "standing" on it's own, even though it's going to be pushed between the couch and the wall, so it doesn't need to be too balanced. But I would like to make it as balanced as can be. I also want it to be flush against the wall, and I have baseboards, so I assume I'll need to cut a small piece out of the bottom that will be where the baseboard is, so it can be flush.

  
Any tips and guidance would be greatly appreciated. Even wood and stain recommendations.

Behind Couch Shelf