first, why is it that i can't post in general forums but i can everywhere else?

second, does yoricks abilties crit? like GP's "Q"

1) I have no idea D= Try asking over on the support sub-forum?

2) The only two skills that can deal a 'true' crit are Garen's Spin to Win and Gang's Paaaar!ley. All OnNextHit skills can crit, but the bonus damage from the skill won't be multiplied. Only your base/bonus Attack Damage.

That includes the second hit on Shyvana's Q as odd as it seems.