That is stunning! As for cleaning, I stick to sewing machine oil and silver polish (for shiny parts) on my super oldies. With that mother of pearl I would be very reluctant to use kerosene or any other type of solvent. Often times they painted over the mother of pearl to give a lovely iridescent glow to the design, but the paint over the mop comes off very, very easily and requires delicate care to avoid removing. I usually take off the tension assembly and other parts that remove easily for cleaning (take photos along the way to remember how they go back on).
Looks like the arm is silver plated as well. I always go gently with the silver polish on these parts also as the plating is not thick and can start to come off if cleaned aggressively. I am of the thought that I would rather have a tiny bit of grime and dirt left than to risk damaging the finish or decoration of a machine. Most of mine come quite clean but I don't expect them to be spotless.
The bobbin winder is spring loaded on the left side to allow the bobbin to be held tightly. Under the bed of the machine (on my model) is a post for adjusting the stitch length. It is in the back center, a bit towards the left.
In looking at your machine, I would pull it from the table and give a good oiling all over, inside and out and let it sit for a bit before gently wiping it down. Then polish the shiny parts and put it back together. It really is in great shape!
Suzanne