To attach cabane struts to their scale locations requires that they be attached at the spars. But drilling a hole in the spars is not a very good idea. How do people deal with this problem? Also, just generally, how have you dealt with wing attachment on your biplanes?

A related area of personal ingorance is how exactly "hinge and pin" type lower wing attachments actually work. I can see how this holds the wing against the fuse but I don't see how lower wing dihedral can be set using this technique. Is it the case the the lower wing is literally hanging below the upper wing -- supported by it? Is the answer all in proper set-up of functional rigging?