Zend Server Update

Hmmm...can't seem to see what I need from the Zend site. I am currently
running an older version of Zend Server on my i - from phpinfo, it's PHP
Version 5.2.12. I was looking at some forum threads, and saw there was an
SP issue, and an upgrade fixed it.

Question: How can I tell if I'm running CE or not? I assume I want to
upgrade to the same version. I guess the question is whether a license key
was entered, right?

Question: Do I have to worry about the procedural vs. OO thing, or is that
all resolved in 5.3 and up?

On http://www.zend.com/en/products/server-ce/downloads, I see *Zend Server
for IBM i (PHP 5.3), Version 5.6.0. *Is this what I want to install? And
then do I need to install *Zend Server for IBM i *5.6.0 Hotfix 5 (PHP 5.3
only)?

Thanks!