Google is your friend.
From the
News Shopper (SE London/Kent):
Following successful talks the Oyster▸ card is set to come to Dartford and Swanley, a move which has been greeted with joy among north Kent commuters.
Southeastern and Transport for London made an agreement on September 11, with the Oyster card system set to be in place by December 2016.
Commuters travelling to and from London have been frustrated in recent years as they are only able to use Oyster cards for part of their journey.
Dartford MP▸ Gareth Johnson said a more joined up approach will make life much easier.
He told News Shopper: "Dartford commuters have been without Oyster services for too long.
"I have had constituents getting in touch with me asking if it can be brought into the area for years. It should make things a lot easier.
"Before it was one system from Dartford and another once you're on the underground.
"And it's always been an anomaly that we could use the Oyster cards on buses in Dartford but not trains.
"If they don't want to use Oyster people can still use the old system. I cannot see a downside to it."
Shashi Verma, Transport for London's director of customer experience, said: "We will be working with the Department for Transport and Southeastern on their commitment to introduce Oyster to Dartford and Swanley.
"We look forward to seeing it extended further.^
A spokesman for Southeastern added: "We are working with TfL» to introduce Oyster to Swanley by 2016.
"This forms part of our Direct Award contract signed off by the Department for Transport last week."
(...continues with vox pops).
No word on the Zones, but I imagine it'll be a similar set-up to places such as Brentwood, Shenfield, Grays, and Watford Junction which are in Zones B, C, G and W respectively. These, along with 7, 8 and 9 are discrete geographic zones rather than complete rings like Zones 1 to 6.