What distribution are you running? If you can install PG off of packages (RPMs, DEBs) it'll be easier on you.
Was the postmaster already running when you tried starting it? If not, remove the /tmp/.s.PGSQL.5432 file before trying to start it. You may have killed the postmaster in a previous attempt and that left the socket lying around on /tmp. (BTW, it's a REALLY bad idea to kill -9 tho postmaster. Tom Lane described it as "shooting yourself in the foot"). You should use pg_ctl to start and stop the postmaster.
As for the libraries, psql and other applications need to be able to find the PG libraries. If you put the libraries somewhere where they already know where to look for (e.g. /usr/lib) then no problem. If you want to leave them in /usr/local/pgsql/lib, then you'll have to add that directory to /etc/ld.so.conf and run "ldconfig".
I think I described this in the "Simple PostgreSQL installation guide", (part of the OpenACS docs).
