Good day/night FP friends!

Just want to ask a few quick questions about Pelikan piston filler fountain pens:

  1. Are the piston filling mechanism and instructions the same across all models, i.e. the M series from M200/205 to M1000/1005? I noticed that the piston threads look a bit different, e.g. the M205 and the M805.
  2. Is there supposed to be a slight "step-up" near the piston knob at the end of the pen? I.e. when the pen is capped, when you move your finger across the pen from the end of the pen to where the nib-side is, there is a slight "step-up" at the piston end and it's not completely smooth. If so, would you consider this a design flaw?
  3. Do you have to lubricate the Pelikan piston on a regularly basis? And how/where? Some people online say you do, some say you don't. Some say use silicon grease, some say never use silicon grease.

Sorry guys, please be patient with me! I am a Pelikan noob.

Thanks and have a lovely day. Carpe Diem.