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.
I can't speak to the Bolt since I've never seen one.