The lift pins sit in a block of plywood which in turn fills the gap between the rib and the face of the wing skin, as can be seen in the photo. They go almost all the way into that plywood, so they run inside for maybe 3 - 4 cm. Note that the structure of the lift pin inside the plywood has a larger diameter than the exposed part and is hollow on the inside.
The rib makes sure that the torsional and especially the lift load is well distributed. Since the area encircled by the wing skin is much larger than that of the spar, almost all torsion load is carried by the skin.
Loads go where the stiffness is. In the end, wing skin and spar will bend equally or the wing would disintegrate. Therefore, the strains are the same and the stresses are distributed according to the relative stiffness of the parts.