I just had the head off mine the other day and noticed the brown carbon had a few shiny spots right in the middle where it had flaked off. Tuned right it always looks about like this. Some carbon, not too bad. When I was running it rich for break in I did clean the piston crown and barrel once, with a wooden popsicle stick, a stiff brush and seafoam. I thought it softened it up if I wet it and let it soak for a while.
I just run regular 2 stroke oil, I figure the engine is primitive so its oil might as well be traditional. Plus its cheap and I like the smell.