Sync 20 diferent sites, 2 way, different installs?

Hello! I have created aproximatelly 20 WP/BP/Mulstisites and I need to know about this plugin:

1. Can I sync more than 2 sites (20)?
2. All sites are different domains, WordPress installations and different hosts. Can it sync anyway?
3. Once you set the main site, it syncs 1 way or 2 way? (all users go up to the main site only or all users get replicated on all 20 site?)
4. Do they all have to be WP/BP/Multisite? or can I sync the users of single non BP non Multisite also? or any other combination?

Thank you!
Donald.