RE: Balancing a canard or tandem wing biplane for initial flight.
For forgiving handling, a canard should be balanced slightly nose-heavy by about the same amount as would be indicated for a conventional tractor layout. A good way to check this is to make up a profile fuselage small cardboard hand-launched glider with the same relative wing and stab areas and tail moment arm, and test for stable glide with various CG locations, courtesy of paper clip nose weights. A six inch wingspan is adequate for the little glider, and flat-plate non-cambered airfoils are fine, as far as CG is concerned. This little trick should get you within a couple of percent of wing chord of the best CG location, although test flying of the full-size version may indicate that some fine tuning of CG is needed. Always start a bit on the nose-heavy side.