My guess is that onboard power for heating, communications, computation, etc., will probably be supplied by rtgs in early missions, a technology we're already quite good at.
Not to the 50 Billion mile mark. It would take close to 100 years to put something that far out. Next and what is quite possibly the killer in this story is retrieving that data. At the speed of light, it would take 75 days to receive the signal. The amount of energy to transmit reliable intelligence across that distance would be immense. Bottom line, what could we gain by such a venture? Since it is, for all practical purposes, impossible for man to sojourn to some distant (potentially) habitable planet, the only reason would be to get the ultimate snapshot.