Unfortunately, I did not understand the well question, because is not explained the context.

But I will try to reply.
2. Yes, when I required field is hidden from conditions the field become optional
3. and maybe 1. You can create a menu item (or module) to show only user that meet SQL Custom Where parameter. You can find documentation here https://www.easy-profile.com/docs/69-sql-custom-where-list-and-module.html. Still is possible to set SQL Custom to use the current loggend in user values with our Content Plugin (docs here https://www.easy-profile.com/docs/26-plugin-content.html)
for example, get user with my value in field with alias field_test:

field_test='{user avatar me raw}'

You can not get the user filtered by URL, but you can create a menu item of type list and set in SQL Custom where something like this:

aboutme='Manager'

Now you have a menu item with own URL.
4. Sorry but I not understand