1) The PV roof (which was clearly meant to be for the car, not the owner's house) would be a great standard feature.
From an engineering perspective, it wouldn't be enough to charge the propulsion system for the car. [Also, Lutz's comment that the volt would be programmed to sell power back to the grid while it is parked in the garage needs some work since I'm guessing that the PV panel wouldn't generate much when garaged].
However, it would be a great way to power up for accessories such as Signal/Hazard lights, GPS, radio, On-Star, maybe even heated seats. This could be a foolproof backup power option in case of an engine fault.
2) Regarding the price, recognize that there are Tesla Roadsters selling for $110k. I'm sure that the first two years of Volts will sell out. After that, as Lutz said, there may be a proliferation of EV models to tailor to different segments (cheap vs. luxury).
Since they are rushing the Volt to market and focusing on the technical hurdles in doing so, I would expect that the marketing plan would evolve over the first couple years as they get some customer feedback and are able to refocus from the technical challenges to the business model.
Speaking of business model, it seems that the EV/Hybrids have a different value proposition from ICE cars in that the EVs cost more out of the box but have lower ownership costs vs ICEs. This is not just fuel, but largely in the servicing. I'm not sure that they will have reliable estimates of the total ownership cost for the Volt before year 2-3 of production.
On this basis, it might make more sense for them to sell the Volt in a fundamentally different way than they sell ICE cars. Once they get a good idea of what the ownership costs of the Volt are, I would actually have the Volt exclusively on a 4-year lease plan with service included (via warranty)
and an option to buy after that point. That way they could spread out the ownership costs of the Volt over the plan and make the price point much more competitive with the equivalent ICE option if you factor in the servicing, etc.
3) If this truly represents the future of GM, then at some point down the trail, the dealer model needs to be revamped as well. They may well wind up going to a Saturn dealership-model for the EVs.