After putting some thoughts into these issues, I came up with an inexpensive, easy one day project to solve both problems.
1" wood strips
Green plastic landscape fencing
LED Christmas lights (1 strand)
Thin L brackets (to attach wood pieces together)
Rigid Wire (to attach top of wood pieces together)
Nail Gun (used brad nails)
Staple Gun (to attach fencing)
Drill (to drill holes to run wire through)
Step 1: Creating the Frame
Cut the wood to fit: (Sizing depends on how large you want your tree-plus you will need to tweak the frame to fit your corner)
For Vertical you need:
3 Pieces the same size
2 Pieces the same size but about 2" shorter than the other 3
For Horizontal you need:
1 piece (goes across the back-so length is determined upon the size of your tree)
2 pieces same size (these are the angled side pieces-so again length is determined by how far you want your tree to come out from the wall)
1 piece (goes between the angled side pieces to make the front)
To assemble your frame:
Take the 2 pieces for the side angles and cut one end of each at a 45 degree angle. Attach the shorter horizontal between the 2 angled pieces.
Attach this assembly to the longer horizontal piece.
NOTE: We attached the assembly UNDER the horizontal piece using 1 loose brad in each end. This allowed for adjustments to fit in the corner prior to final tightening.
Now assemble the verticle pieces:
Of the 3 longest pieces-1 on each corner of the horizontal assembly and one in the center of the front piece of the horizontal assembly.
Hammer the thin L brackets straight and nail to the wood pieces.
We used the brackets so that we had flexibility in shaping the wood to the corner. Initially we nailed the wood together and found it to rigid and it didn't allow for tweaking.
Drill a hole through the top 3 pieces and join with a rigid piece of wire.
Again-this allows for fitting into your corner. Once the fit is right--make sure your wire is tightened.
Now repeat the process with the last 2 pieces of the shorter wood. Place one piece on each of the angled side pieces. Attach to the longer horizontal pieces by drilling a hole and securing with a piece of wire.
Check your fit in the corner and tighten wires and nails accordingly.