RE: Ola - Harness line length
I agree with Doby its very individual. Run what feels best. However, its good to test around a bit and give different settings a fair chance (ie trying a higher boom, longer lines etc to see what that does for your sailing).
I personally use 26" lines (I'm 1.76m) and use my boom a bit above the mid point in my sails (boom center at the 122-123cm mark on my Hot sails). I use a waist harness.