Обсуждение: PostgreSQL on Amazon EC2/EBS

Hey!
I'm trying to install PostgreSQL 8.4 on my Amazon instance. I've found
this guide: http://tinyurl.com/y2tcmd8 . Can someone take a look at it
and check if I won't break anything following this article?

I'm especially concerned about this XFS file system. I've already
installed bunch of stuff on this instance. Will adding XFS break
something?

Second question: I'm supposed to add my IP in pg_hba.conf file. But
what if I have dynamic IP? I certainly can't change it every time I
want to connect to my database. What if I put 0.0.0.0/0 there? Is it
very bad practice?

Thank in advance for taking time to answer my noobish questions :).