As far as the diary at Amy's wedding goes, that makes a little more sense now that we know that River is Amy and Rory's daughter. We saw her for a moment at the wedding walking outside, so logically she must be time travelling. So it's sort of like a self-fulfilling prophecy, or a chicken-and-egg thing. River exists in Amy's time, therefore she must be a time-traveller. She has the diary, so it's logical to assume that she knows the doctor in the future-- which means Amy must have remembered him. So River drops the diary, Amy remembers, River is born, meets the Doctor, gets her diary, and drops it at her mother's wedding to make sure that the Doctor is remembered.

tl;dr spacey-wacey shenanigans. Did that make any sense? The logistics of time travel make my head hurt, so it's likely it didn't :/