1. In general, **acid** + $H_2O \rightleftharpoons$ **base** + $H_3O^+$
2. It is called the henderson-hasselbach equation
$pH = pK_a + log\frac{[base]}{[acid]}$
3. I believe the equilibrium constant for a such a neutralisation would look like $K_n = K_aK_b\frac{1}{K_w}$