BuddyPress.org

Hi!
My question looks so simple but I did not find a decent answer anywhere online.

I want to use BuddyPress on my website.

For now I use WP User Manager for people to register and I use WPDiscuz for users to comment.

1. Will Buddypress take over all my existing subscxribers (around 2k) or can I do that somehow?
2. Do I need to delete WP User Manager?
3. Can I keep working with WP Discuz?

Thanks a lot in advance!