I tried to describe the hub removal process in my last post about this. It is usually pretty stubborn, but you have to loosen the hex nut that is behind the freewheel sprocket. I bought a pair of channel lock (the brand) pliers that have blue handles and a notch in each jaw. The points on the hex nut fit right in those notches, and the pliers are thin enough to get in between the sprocket and the hub. They will allow you to get enough torque to loosen the nut. Once you have loosened the nut, the freewheel/sprocket will unscrew. Then you slip the mounting bracket off and that will allow the whole hub (brakes and all) to slide out the other side.
I'd just swap the hub. The Bravo uses a fatter tire than the Ciao and might look funny. I don't think the low end will be noticeably better. You will gain enough just with the variator addition.
You have to use the longer shaft, because the Ciao shaft is made to hold only the driven pulley. The Bravo shaft has to hold the whole clutch assembly. Once you've cleaned the clutch, it should work fine.
Let me know if you need any other help. If need be, I could send my phone number and can talk you through any difficult spots.