Your observations are right on the money! Yes, the distro has very few examples. The older .3r77 has more samples available, but many of them are not compatible with the .4x release, as the author has done a major redesign of the object structure. (I'm still trying to grasp it...)
One minor point: fillstroke is just one option for "painting" glyphs or objects on the page. There are also separate "fill" and "stroke" functions. The fill method fills the "inside" of the object or glyph, whereas the stroke method draws the border. This permits objects to have an outline color different than the fill color.
When I get a few minutes I'll play around with the sudoku thing and see what I can come up with.
UPDATE: I did my first sudoku puzzle - very cool! I can't believe I'd never tried one before. Anyway, that helped me to visualize what to do with the PDF stuff. I am working on a few things with the PDF files - multiple puzzles per page and multiple pages per PDF. I'll keep you posted on my progress.