Hey landwire,
I’m trying to achieve (mostly) the same thing as you. So far, I’ve been able to change the upload path for images using the code found here. I have set my new upload path to an existing gallery. Thus one has to create a new gallery beforehand, this is not done from within Gravity forms..
However, I still have to manually rescan the gallery from the ‘Manage gallery’ page. So any tips on how to get the gallery to update itself when the Gravity form is submitted would be very much welcome.