Just wondering what happens after a paid listing expires?

- Does it go 'unvalidated'?
- Or does it just drop back to be a free listing?

I'm looking to set up my directory so I have a basic free listing, and then paid listings each of which display more information in each link. So what I'd like to know is...

- Is there an easy to way to have paid links drop back to a free link when they expire?
- If I set up listings - Free, Bronze, Silver, Gold - can I use these tags in the link.html template with "if" tags to hide information depending on the payment level?
- Can a user currently 'upgrade' to the next payment option in the system? ie. if they purcahse a Bronze listing but want to upgrade to a Gold, can the system handle this or is it possible to implement?

Thanks!

Regan.