I'm going to do a small webshop (yeah i know there are loads of free ones, Im doing this just to learn php better

So I will make the page a class with variablles like
private $keywords;
private $title;
private $buttons; ... and so on.
Each time a user clicks on a button a new page will be drawn with new content.
My question is how will I do this in the best way. I do not want to do a database call (for the page settings anyway) everytime the page loads (only the first time every session).
Should I store the values in session info after initial call to DB and check with isset later on or are there any better way to do this?
Thanks in advance.
Edit: Oh and how secure is the session info? Say I have users with a userlevel that sets permissions.. can I store userlevel in session info or is it better to do a db call for userinfo when trying to access admin functions? /edit