Can I set a free level to collect email addresses?

Yes collects reader info before subscribing (requires adding some custom data fields) and also offer a few Free articles in return for an email address.

Create a level with a price of $0 and it will generate the free level subscription (the free level require registering). So you can dial your meter down to say a couple of articles and then encourage readers to register for the free level to get a few more articles.