Bitubo front fork information.

Hi all. My first time here. I’m rebuilding and modifying some Bitubo (I think) 40mm front forks that I’m guessing came from a California 3 Guzzi. They have the adjustable preload and damping above the top plug. The damper unit is of dismantlable design.
I have four questions. 1. What sort of oil is correct for the damper cartridge? 2. Is there any advice about removing the cartridge lower plug? 3. Is there a torque wrench setting for the main top plug (with 38mm hex.)? 4. What is the correct orientation for the (presumably) oiling holes in the lower end of the stanchions?
Thank you in advance to anyone that can either answer these questions or point me in the direction of where answers might be found.