ok, I started this thread two months ago, and have since gotten to know WP a little better.
Beee, you’re right it’s the post slug that generates the URI, and it stays the same even if you change the post title. I never experimented with changing the category though but I’d assume the post slug would remain the same in that case too (I opted to use the /%postname%/ permalink structure also).
Another good thing I found was that if you accidentally (or intentionally) publish multiple posts with the same title, WP will add a number to the slugs of the subsequent posts so that they all have unique URIs.
