Zoho wiki Groups, Contacts, Workspaces questions

Page https://www.zoho.com/wiki/enterprise-wiki.html gives an overview of Workspaces and Groups which looks very useful, especially combining the two.

However, I'm having difficulty discovering how this is reflected in the product, possibly just due to my failing to discover docs.

1. Docs talk of "Enterprise Wiki". This is just a way to use the more sophisticated features of ordinary or paid zoho wiki, right, not a separate Enterprise Wiki product?

2. Contact List: As described on https://zohowikihelp.wiki.zoho.com/Wiki-Permissions.html (and its presentation) the Groups functionality seems to revolve around somehow managing users in a "contact" list and assigning them to groups. But:

How do you get to the UI for managing contacts?
How do contacts correspond to existing users of a wiki?
Can existing users be joined into a group?

3. General group concepts:

Can a user be a member of more than one group?
If a user has permissions via membership in two groups, where the groups have different permissions, does the user get the total of all permissions?

4. Workspace concepts:

Having created distinct workspaces, does the search function search across all workspaces (assuming user has read permissions on them)?
I believe there are separate Settings pages for the overall wiki, and for each workspace. When looking at the Settings page, how do you determine what it's for -- which wiki or which workspace?

Thanks!