Ok, I’ve printed the documents. Much easier to work with paper rather than the iPad.
The hardwood wing strut support pieces run parallel to the fuselage sides which you have figured out. One way to check this is measure the distance from top of longeron to bottom of hardwood support. Cut 2 pieces of wood to this height and long enough to span from one side of the airplane to the other side. Place these pieces one by F1 and one by F3 across the fuselage. Place a straight edge on top of these pieces and mark your formers. This mark will be the bottom of the hardwood support. Doing it this way will be equal spacing on both sides of the fuselage. From that mark you can measure for the notch in the former. You may have to plane the outside edge of the hardwood to follow the curve of the formers. Any cuts you now have in the former that do not line up can be filled in with a glued in piece then properly cut the notch. You can reinforce, if needed, with a gusset glued on three sides of the hardwood and glued to the back or front of the former. On the bottom of the hardwood support you will glue in the plywood wing strut attach plates. The bolts go through these plywood plates and hold the wing struts. These bolts do not go through the hardwood supports.
You can do the same to the formers F4 to F7. Add gussets if needed. I agree that the leading edge of the wing requires a ¼ by ¾ or ⅞ piece. The ¼” square you are seeing may be the pieces needed to install the leading edge wing slat.