You too!
See the FAQ: Why doesn't the auto-updater detect the latest version?
Add/Remove Programs is where the uninstaller is found. (Putting Uninstallers in the Start Menu as well as, or instead of, Add/Remove Programs is against Microsoft's guidelines, although plenty of programs do it.)
Yup.
Yup. There are no update installers, only standalone, full installers which you can install over an old version or on to a fresh machine.
So long as your licence is valid for version 9.x it will work with all 9.x installers.
It sounds like you've changed things in a few different places so there probably isn't a single checkbox which covers just the video-related preferences.
If you do want to reset just some preferences then you can do what I said earlier in the thread: For Opus's own Preferences each page can be reset using the File menu. For plugin Preferences you can either use the Defaults button in the plugin's config window (e.g. in the case of the ActiveX plugin) or delete the plugin's config file from /dopusdata/ConfigFiles/Plugins and restart Opus (e.g. in the case of the Movie plugin which doesn't have a Defaults button).