Should I set up the ailerons for differential operation or just mix aileron with rudder? What are the performance trade-offs of each setup. I do fly inverted and which method interferes the most with inverted flight? Also what would be good setup percentages for this plane? Thanks much for any info.

Remove most of the diehedral. I put enough in so the wing doesn't look drooped. Offset the aileron push rods for a little differential. On a plane with very little diehedral the rudder will work backwards when inverted and cause yawing when the plane is banked with the ailerons. Don't couple in rudder if you are into aerobatics.