It is a ridiculously well engineered car. Way more power than the competition, bigger battery than the competition. The 2009 model is still technically ahead of all the other plugins on the market.
It doesn't matter for the Volt. Since it has a range extender, there's no real need for fast charging. Just charging it every night from a 120V outlet will eliminate most gas usage for most people. If you run out of charge, it's an annoyance rather than a disaster.
I can't speak to the Bolt since I've never seen one.
It depends on your mileage. 4days to fully recharge from empty, if you are on a road trip (which you obviously couldn't do in a Bolt). But overnight it will charge 50miles, which covers local daily use.