Hi,
thank you for your interest in our product

with redirect for usergroup and custom redirect

This is not possible, you can manage this only by develop custom plugin*

Is it possible for a certain usergroup manager to add, user to a specific group??

Only from backend.

As by default there should not be an option for the standard user signup to set its own group.

Easy Profile extends Joomla user profile, so standard registration group is set into Administrator->Users->User Manager->Options->New User Registration group parameter. With Easy Profile you can add/remove usergroups with conditions based on field value.

And finaly, does the user system store info from social-login (FB, etc.) ??

No sorry, our product provides only Login/registration, we get only firstname,lastname,avatar and email** from social networks


* we not provide and do not support custom plugin
** Twitter never share email address, so after registration via Twitter our system require to fill email address.