I was just about to update my installation, but it told me that my Roboform extension isn't compatible with v7.
If they allow the application to update when it wants, they're going to quickly render me unable to use Firefox, since I won't be able to log into secure web sites.
Did you receive the update automatically, or did you download and install it manually? If you are using automatic updates, Firefox should ask before updating if any of your add-ons will be disabled.
My experience is that if I click "Check for updates" and an update happens to be available, then there's no way to prevent that update from being installed, even if it causes add-ons to be disabled.
Yep. You only have to download the update if you don't want to wait the up to 8 hours before your browser pings the update server and discovers there's an update.