X's two on having nuts. Over time the vibration will destroy the threads on the push rod at the clevis. (there is a bad joke in there somewhere)

As for the firewall. I like to add some cloth either inside or outside of the firewall. Especially if you are installing a 120SC on the nose.

Wing. I like to use cloth top and bottom of the wing. Glass where the fuse touches the wing on top and on the bottom glass out to the retracts. Additionally, check the retract rails and add glue... they usually fail.

Jimmy Skids