If you are an Ariba on-demand (Cloud) customer, you should have access to the downstream enablement workbook which will have a tab names "User Roles". This sheet defines all groups and whether its a user or team member license and definition as per each Ariba module. You should be able to find this in the ariba connect site or raise a service requestwith ariba support team and they will share it with you. Your points 1 and 4 above will be answered alone by this sheet. For #2 and #3 you may check available pre-packaged reports to see if this info is available there or else file and enhancement request if you need that information for your business case.