Yes, but I wonder if there'll be a more limited range of angles at which you can hold the controller relative to the cameras before you run into trouble with occlusion etc. With the sphere you could pretty much angle the controller any way you like, except with the ball turned directly away from the camera, I guess.
Then again, we don't know how they intend this to be used yet. It'll be interesting to see the suggested use-cases for a two handed controller with that kind of tracking. A one handed controller mapped nicely to many things (sword, racket etc.).
A cable, two lenses in one box.
Unlikely, IMO - the system needs to know the distance between the two lenses and their angle.
No. At least usually you'd have one or the other I think. There are systems that fuse stereo with ToF data but I imagine Sony is looking at cost here and what they actually need.