student learning pgsql/linux5.0 redhat

version postgresql = v6.3.2 ,(version shipped with linux redhat5.0)
o/s = linux redhat5.0

After installing postgresql,postgresql-clients,postgresql-data by "Package
Management with RPM' I am have problems understading the system layout as
shown in www.postgresql.org/doc/postgres/layout.html.
On my system I am unable to find  'all' the files belonging to postgresql.
I can find /var/lib/pgsql files, but that is all, my drive is divided up
like this:-
/dev/hda1 = /
/dev/hda8 = /usr
/dev/hda5 = /usr/local
/dev/hda6 = /var

Also during  the boot process the system starts executing some runlevel
scripts
 & during this  it outputs a messages  that looks something like this:
"Executing some Sysv init scripts
 Executing: /etc/rc.d/rc3.d/S85postgresql start
*Fatal: StreamServerPort: bind() failed:errno=98
*    is another postmaster already running on the port
*    If not, remove socket node (/tmp/.s.pgsql.<portnr>)and retry
*    /usr/bin/postmaster: cannot create Unix stream port
    >starting postmaster service:postmaster [ ]

A] How can I check  to see if another postmaster service is running, and how
do I resolve this issue.

B] Where is the startup script  for postgreqsl normally stored.

c] Thank You for you time !