What's "pure" black

Hi Everybody,

I have three questions.

1.  I can't find a definition of "pure" black on the internet.  See color tab in print dialog.
Is it (0, 0, 0, 100) or (92, 79, 62, 98) (rich black).

2.  What does the check box do.  I have not seen any difference when converting sRGB to CMYK if the box is checked off or not.

3.  Just to save the cost of colored ink, is there a way to get a photo to print sRGB black as (0, 0, 0, 100) on a consumer level printer. I can live without rich black.