Steve, idaho is a bit far for me to show you in person, but if you happen to be over in Western Washington, I'd be happy to show you the centerboard setup.
If you look at this picture here (from wikipedia)
It's the red with white fleck line that goes from the centerboard and through the pad-eye near the mainsheet block. With the board down, you pull it tight and then jam it in the cleat to keep it down.
I'm unsure how to rig a spinnaker on the C-Lark (mine doesnt have one nor the rigging) but I do it all the time on a big boat. Need 2 lines that typically run back to the stern quarter on each side. One becomes the guy (controls the pole position) and the other the sheet (controls the clew of the spinnaker). When you gybe, they switch jobs.
Feel free to shoot me an email if you want to chat more.