I think you need to temper your expectations. Where Oyster is valid outside zones 1-6 it is rarely cheaper than alternative payment methods. The same is true for contactless PAYG. The technology behind Oyster is quite dated now and cannot be extended in it’s current form. PAYG fares from Medway will match traditional fares if/when it is extended. The only difference will be that singles will be half the return fare.
I’m sorry I have no information on bus services.
