Upgrading from 9.0.11 to 9.3.5 on CentOS 6 (64 bit)

Hello,

I have Postgresql from a few years ago. That's 9.0.11.

During the vacuum it's basically crawling to its knees. While googling
for this (it stops at "pg_classes" forever) I see Tom Lane suggested
upgrading.

So now I must. In doing so, can I follow these instructions?
https://www.digitalocean.com/community/tutorials/how-to-install-and-use-postgresql-on-a-centos-vps

I want to make sure all my data remains exactly as it is, and the
pgbouncer on top of PG (helps us a lot) also remains on the same port
etc. Just want to confirm that whether I update via the RPM method, or
the YUM method, that the settings in all the places will remain?

Ideally, I don't want to be linking new paths and so on as I see in
online instructions on blogs. Many of them (e.g., the official post
here - http://wiki.postgresql.org/wiki/FAQ#What_is_the_upgrade_process_for_PostgreSQL.3F
) also speak of "clusters". I don't have any, or is my PG basically
one cluster?

Sorry for the noob question, but it would be great to get some simple
to follow, step by step guidance. MySQL etc are so simple to upgrade!

Many thanks,
PK