If I use any of the common V-Mount batteries to feed the electronic gadgets with power, (Switronix Hypercore for instance), what device would be necessary to use if I wish to supply power and distribute it evenly if I have other gadgets attached to video camera (e.g. viewing monitor, motorized follow focus, external recorder, etc.) ?

Location sound mixers have been dealing with this issue for a few decades. When you have multiple wireless receivers, a comtek transmitter, a mixer, and a recorder in your bag it gets a bit ridiculous with multiple battery types. Something is always dying, do you have one charged?

Forum sponsor B&H has a whole category devoted to Battery Distribution Systems. (http://www.bhphotovideo.com/c/buy/Battery-Power-Distribution/ci/5693/N/4291085907)

I've not seen anything comparable for video rigs; it's one of the things that soured me on rigging a dSLR to function as a camcorder. Now with Canon's Cinema EOS price cuts I expect less dSLR rigging. But the audio BDS systems from PSC and Remote Audio would be a good start; you may need to custom some cables...