It looks like Scrivener ships with a version of the growl framework which would install Growl when prompted by the user, and it hasn't been updated in a while. This is why the update button does not give you an option to click it, the framework being the installer version (at least that's my best guess here). You could open up the app bundle from Scrivener and put the updated version in there manually, however I do not know if this would cause any problems within Scrivener.
I would suggest asking Apple for a refund first off for Growl. You can continue to use Growl (I believe this is how it works) as far as I'm concerned, but I feel this is the best route here just for this portion of things.
Regarding Scrivener support for what you wanted, I found this: http://www.simplyscrivener.com/tag/word-count/
which seems to be helpful. I don't know if it covers what you are looking for but it does look helpful. Other than this I would suggest contacting Scrivener support to see if they have any other suggestions here.