Switch profile - proper approach

Hi guys

I have some questions regarding switching profiles for a user.
My setup;
I have these four Joomla user groups;
1. Registered users on the site
2. Club members
3. Publishers
4. Admins

I created four corresponding ES profiles. Paying members (registered users) will be manually set to club members. They get access to some Joomla articles and access to a thread in Kunena. The Publishers has access to create event in certain event categories.

Question 1 - the image below, how to think about "Also, switch their Joomla user groups as well"?
I don' really understand what this do.


Question 2 - I created same profile fields for Registered users and for Club members (I have named them the same, nothing more). When moving a registrered users to become club member I got a warning about they have to update their field and data will be lost. But it seams after the move the field data is there. How come? Is there a better approach?