New side handle for Ursa Mini

That would be incredibly useful.

I'd definitly need more options on the handle, like customisable arrows, to change the shutter angle.
A zoom in/out button, to replace the double tap on screen and focus easily (mine doesn't work ? Am I the only one ?).

I am more of a run n gun shooter, and a new handle could be so much more practical. Anyone else ?

Nice idea, but you are not going to easily get those added functionality from just changing the handle, or via LANC, which is what the current handle uses for focus and start/stop. You will need an interface similar to the SBus on the Micro cameras, or an Arduino Shield interface built into the handle, and utilizing the SDI return connection, which would interface with the camera as it currently stands.
Cheers

for the ursa mini Bluetooth would probably be the best option (again you could implement this via an arduino or similar micro controller)

not as robust as wired but you do have full camera control I believe through their Bluetooth API (has this actually been published yet?)