contributing patches

These may be more -hackers questions, but I am duly following protocol
by trying elsewhere first.

1. Does the PostgreSQL development team require the assignment of
copyright in order to accept contributions? If so, is there a standard
form that is normally used for this purpose? Or, alternatively, do I
need to provide something that says that my employer does not assert
copyright over code that I submit? (i.e. it's mine, not theirs)

2. My understanding is that we are currently in feature freeze for 8.3.
I think this means that it's a bad time to discuss features for 8.4, or
to provide patches implementing such features. Assuming that's the
case, when would the appropriate time be?

Thanks,

...Robert