Hi OCaml folk

I apologize if I've been asking too many questions on this list 
recently, but I'm working on a heavy OCaml application and need help 
sometimes.

I am having a disagreement with a colleague about how the equality 
operators in OCaml work and am trying to resolve it conclusively.

1) I understand that the '==' operator is basically a pointer comparison 
i.e. a==b true  iff a and b are the same entity. Is this true?

2) Where can I find the code implementing the '==' operator in the OCaml 
code?

3) In case I do want to check object identity and can use the == 
operator, would it be faster to use '==', '=' or a match statement?

Thanks
Raj