Questions about the film

Rating: 9/10 (17 August 2003)

Spoiler!!! Hey guys I just finished watching the movie and have a few questions:
1) How was Sammy a faker and didnt have a wife? Where was this in the movie? I dont fully understand this point
2) How can Lenny be Sammy? If ppl are saying that Teddy was lying then the entire story is bull..isn't it?
3) More on the Lenny is Sammy thing...how can Lenny be Sammy if Lenny fully remembers his story..doesnt that mean this happened before the accident or else Lenny would not be able to remember it?
Thanx in advance for the help