Recent installed 7.3.4 startup doubt

Hello;
I've recently installed postgres7.3.4, from the source, (my first time) and
just got a good result with the dumpall, thanks to you.
I have some problems with the client pgAdminII, bu I guess this is not a
proper place to pose those problems.

Well, my doubts are:

1) How could I see and change the server encoding? I think that perhaps this
is a source of problem for the client pgAdminII (I've put client_encoding in
postgresql.con as 'sql,european').
2) I'm only able to start the server from the user "postgres". Is it possible
to start it from another user? The problem is that I usually work as other
user "javier" in my computer, which is where the server is running, and from
the user "javier", when I do: su - postgres, a password is requested (this
doesn't happens when I do that from root. "?") and I don't know that password
nor start the server.

Can you give me a hand with this?

Best regards

Javier