The answers to your questions are all going to be based on opinions. For whatever its worth...

1) Taking a PDC is important. Spending time around on-the-ground permaculture operations is great too. I think there might be an advantage to taking the PDC first as it'll prepare you to make better sense of what you'll see in practice but.. your mileage may vary.

2) Making a living selling produce is challenging for a variety of reasons but there ARE people that do it. You need to be very motivated, skilled at growing, have enough pairs of hands to make it all happen, and creative in marketing your produce to get to a profitable space. I probably wouldn't retire the accounting shoes just yet... have a look at the farmers markets and CSAs around you... look at land options and have a solid plan of attack going in before you take the plunge. In the meantime learn all you can about permaculture and organic gardening... the knowledge will help you a great deal.

Here is a link that might be useful: Permaculture road

Great, thank you so much for your help! Very much appreciated :)