No rotary dial, and... I think no, the closest you'd get is to run an app on the watch (so you can capture the three not-"back" buttons) plus a companion app on your phone to receive events from it and do [stuff]. But that'd mean you'd have to open the app on your watch to control what's on your phone.

The media controls might be able to do the volume part automatically out of the box though? I forget exactly what their UI did when I had music playing, but I think it had volume and skip controls. That's nowhere near arbitrary control though.