Diprotics are a bit annoying...I'm getting a bit tired too but I'll throw down some points.
Strong + strong should pretty much be straightforward (even if it's diprotic, you just gotta do a little stoichiometry).
Weak + strong, you'll get a salt. That salt will have an effect on pH. Remember that each the acid and base will form conjugate acid/bases, and strong bases form weak conjugate acids (and vice versa), weak acids form strong conjugate bases (and vice versa). So it's these "strong" conjugates that will affect pH. So write out the equation for the salt dissociating, identify the strong conjugate counterpart.
Hopefully Borek will come back with some diprotic stuff lol.