Most Rockys are different when it comes to their settings.
IE: The true zero point is rarely where 0 is on the dial. For instance, my true zero is about -5.
Also, the exact grind level will be unique to your circumstances. What bean, how old, ambient temp conditions etc.
Generally, I grind around the 4 mark (true 9) for espresso and around 20 (25) for plunger. You sound like you are in the ballpark on 6.
Next espresso grind, allow some to flush through the chute to clear out any coarse stuff.
As for storing, I only load what I am going to grind right then. I try not to store any in the hopper.