Users Versus Subscribers

Right now: I have e-mail subscriptions through JetPack. It works great. Unfortunately, I’m moving my self-hosted site to a different domain and need to move the subscriptions. Jetpack doesn’t allow that. So, I have to find new tools for this.

Future: In the future, I want to provide extra content to e-mail subscribers. I was thinking of having hidden content that only subscribers (or users?) can access. Alternately, I was thinking that I could include additional links in the e-mail to subscribers, links that I wouldn’t give to other people.

Questions in order to accomplish all this:
1. To get this all to work, should I actually have my blog subscribers also added as WordPress Subcriber-role users?
2. If so, is there a plug-in that syncronizes this?
3. Any other comments on the advantages/disadvantages to adding subscribers as users.

The page I need help with: [log in to see the link]