Ask HN: Equity structure setup by Y Combinator

From what I understand Y-Combinator assists startups with incorporation. A Delaware C-Corp is pretty standard to allow Common shares for founders and preferred shares for Venture Capital firms. Although their are a few questions here.

First the set par value and amount of stocks they usually create in the articles of incorporation? Standard here is about 0.0001 and 1+ million, what does Y-Combinator do?

And when the founders buy their founders shares, do they purchase it at the par value?

And finally do they set it up so the founders have a vesting period? Is 4 year per monthly vest?

These is pretty specific questions not sure if anyone here will know the answers. Thanks.