Questions about login etc

I’m optimistic about making this work as a discussion on our site, now that BB Press is going nowhere fast. Some questions:

1. Will comments on posts look like comments, even if they get created as forum topics in Discourse? I mean the replies etc will still show in posts as a threaded discussion, or will that area just link to Discourse page?

2. Login: On Discourse I understand I can allow for users to sign up using Facebook, Google, etc. Let’s say they do. Will that login then work for comments etc as well? And we have some newsletters for which we use MailPoet, and the ability to sign up is also added as checkboxes to the comment area. When a user is commenting for the first time, they “register” and at the same time tick checkboxes for the newsletters they sign up to. Will this functionality now all belong to Discourse?

Not sure how these integrations might work. Many thanks!