It seems /login is a reserved route - is that correct? When I hit /login in a browser, I am redirected to the home page (this is on a vanilla install without any entries or routes set up).

Is this a reserved route? 
Can I change that so I can use it for my own route? 
If it's reserved, what other routes are there that we should know about?
That is set by the loginPath config setting so yes, you can change it in your craft/config/general.php file.

There are a few other configurable URLs for templates and redirects, all of which are described on that page.