Regarding User Management in Portal

Hi Experts,

I have a problem regarding the assigning Roles for the users.

I have created two Systems, System1 and System2. System1 has same details as System2. But for System1 I changed the "User Mapping Type" to "user" and for System2 "User Mapping Type" property is set to "admin,user".

Below is the setting for System 1:

Below is the setting for System 2:

I have created a user with the name "Satish". When I assign the Group in "Assign Groups" tab selecting only "Administrators", the following groups are getting added automatically.

"Authenticated Users" and "Everyone" is automatically getting added and in the "User Mapping for System Access" tab my System 1 is not getting displayed in the dropbox list. Only System2 is getting displayed. There is no problem with system 2 it is working fine and I am getting desired output.

Now my question is:

Why "System1" is not getting displayed in "User Mapping for System Access" tab?

Why the two groups "Authenticated Users" and "Everyone" is automatically getting added when I add only "Administrators"?

I have created a role and added to the user "Satish" which has some pages. Now I want only this role to be displayed to this user, but this user has control to "Content Administrator", "User Administrator" and "System Administrator". How can I remove this controls for the user "Satish".

But one thing I came to know, that is when I add "Administrators" Group, the Content, User and System Administrator is getting added.

Please help me to solve this problem. It might be very simple but for me it is getting very difficult to solve as I am new to SAP NetWeaver Portal.