postgresql.conf file and logging questions

Hello list,

1.  Where should the postgresql.conf file be to be recognized by the 
service on startup?  currently, it is inside my $PGDATA directory but 
all of its contents are commented out.

2.  I can't find any log files for postgres.  Inside my /var/log/ 
directory, there is an empty
file called pgsql.  What do I have to do to get it to log errors, 
etc.  Is there a difference between normal logging and syslog logging?

Sorry for the newbie questions!

Thanks,
Devin