Selling access to channel

I have a few questions that were not covered in the FAQ for Roku Billing Services:

1. I just want to develop a channel that must be purchased with either a one time or monthly recurring fee. Do I need to code anything extra into the app to support this, or will Roku handle everything?

2. If I have a channel that is currently free and want to begin charging for it, what are my options? Do I have to remove the app completely and then submit a new one with billing services turned on?

Thanks