I have amazon prime, but not all shows are free. I'm assuming we will have to pay for the episodes ALONG with paying for amazon prime?
I am sorry I don't know why people get caught up by Amazon Prime videos and assume a cost on everything because some things cost money. Unlike Netflix, Amazon has a digital video storefront. Unlike Itunes, Amazon has a subscription video. Non amazon materials has the same rules on amazon as it it does on Netflix, prior seasons are free. But since it has a store front like Itunes you can buy episodes, seasons, and season passes.
The one that can get people confused is exclusives. Something free on Hulu or Netflix might be only available for purchase on Amazon, because like I said its one part storefront one part subscription. That said they all have their pros and cons. Netflix has the strongest catalog, and by far the best originals. Hulu has the ability to watch current episodes. Amazon has a larger past season catalog and movie selection than hulu, and you can use the same service for your web purchases.
In the end no. Amazon original shows will have no costs for Prime subscribers.