pg_hba.conf and postgresql 7.2

New to postgresql...I've done a lot of google-searching and searching of
the pgsql archives but haven't found much...

I'm trying to configure pg_hba.conf so that:

1. using a local connection, user postgres does not require a password for any database
2. using a local connection, all other users require password for all
databases

We are running debian stable so we have postgresql 7.2 From what I
understand, the syntax of pg_hba.conf changed with 7.3, making it easier
to do what I want to above. With 7.3, I would do this I think:

local all postgres trust
local all md5

Is there a way to accomplish this with version 7.2?

If not, I was planning on setting a password for user postgres. However,
in that case, what's the easiest way for backup scripts, etc, running as
user postgres to be passed the password?

Are there any online documents for recommended ways of configuring
pg_hba.conf with security in mind?

Thanks for your help.
--
Amy Tanner
amy(at)real-time(dot)com