My pre-IPS site contains a page which we've pushed in print and online media /events. For consistency, I want our new IPS upgrade to keep site.com/events as a page. Unfortunately, I can't create this in Pages: "This folder name cannot be used as it causes a URL collision with another installed application."

It's a clash with the Calendar app.

What can I do? Is it just a case of tracking down the FURLs which contain "events" and changing the word there? Or is there a list of reserved words somewhere?

Unfortunately, it's not possible to do this. Reserved words are reserved and stay so. The best work-around is to create a new URL, and then set the htaccess file to redirect from the long-time one to the new one.