KK with an ace on turn

[jedi]

While I think it's clear that hero needs to bet the turn, what does he do if check-raised by 1) Laggy BB, or 2) unknown SB?

1) If laggy BB raises, I think we call down, but do we call down even if unknown SB called the bet AND the raise behind us?

2) If SB raises, hero has been showing strength the entire way and SB is obviously not concerned about the Ace, is this a turn fold?

And if both people call, do we check behind on the river (if checked to?) Do we pay off 1 bet? Do we pay off 2 bets if SB leads, and laggy BB raises?