there is a source of volatiles "close" by - earth. with all that water in the atmosphere you can build satellites that orbit low and siphon it and other valuable gases like nitrogen off. The Satellites would use aerodynamic effects and the siphoned atmosphere for propulsion.

As for Solar cells there are factors to consider - they would degrade differently than cells in low earth orbit since factors like atomic oxygen and thermal cycling are less of an issue while I imagine micrometeorites are just terrible. Modern cells degrade at at 0.5% per year in LEO. At 1%/year degradation that means you have 85% capacity after 15 years. So we are talking decades for cells once they have been manufactured here. Cells not in the sun would last forever so they do not degrade in storage.

In the case of the diggers I have not done the math on thermal propagation through bedrock but It would all depend on when the people in orbit start building a sunshade at L1.

the pingers are not in the deep ocean. They are whatever depth the water is below 30°. Some considerations of diving change if you cannot or not plan to surface - ever. We are talking open diving bell environments here and heh - topmarines or ü-boats :) They have a very easy source of energy in the gradient between the very hot atmosphere and the cooler ocean water. no need for nukes for power. you distill oxygen as a byproduct of that snorkeling process. main issue would be metals.