pgtune

I just found out about pgtune and am trying it out on my server.

I have 2.5 questions:

1) Are these settings the maximum that the server will handle, if it is
strictly dedicated to postgresql? Meaning if I am running other stuff on
the server as well, this would be a bad idea.

1a) If I have some intense plpython stored procedures, do they run in
the postgresql memory space (ie using the memory settings from the
postgresql.conf, or do they run under their own memory space and then I
would have to take that into account when allocating postgresql memory?

2) If it sets my max_connections to 80 and would like to set it at 300,
what would be the appropriate setting to lower at its expense?

Sim