Fastpasses will be cancelled if:
1) You are more than 30 days out, or
2) You booked a package reservation with tickets, and cancelling the reservation also means cancelling your tickets.
So since you would be more than 30 days out, yes, you'd lose your FPs.
But, even if you were within 30 days, if your tickets are cancelled so are your FPs. Unless you link additional tickets before you cancel.
Dining reservations are completely separate and would have to be cancelled separately.