I do not run the latest version of postgresql but it appears to be correct. If postmaster is running try starting the frontend:
psql
Unless you add the regular user to postgresql you will see some errors.
For documentation see
www.postgresql.org. The first things to do are add your regular user to postresql so it can manage databases. You will need to su to the postgresql user - postgres and then use the createuser command. After that your regular user will be able to create databases.
You can configure postgresql to start at boot. Look at Mandrake Control Center under services. The init scripts tell postmaster where the database is located.
Only if you start postmaster from the command line as below would you need to include the database location
#postmaster -D /usr/local/pgsql/data >logfile 2>&1 &