User management with REST API

Hello! I've seen a few posts where REST API details were asked and the answer was https://support.sugarcrm.com/Documentation/Sugar_Developer/Sugar_Developer_Guide_7.7/Integration/Web_Services/v10/Exampl… 

I also see documentation to create Users https://support.sugarcrm.com/Documentation/Sugar_Developer/Sugar_Developer_Guide_7.7/Integration/Web_Services/v10/Endpoi… 

So, are Accounts different from Users? When would we create a User and when would we create an Account?

Also, the 2nd link above for Users talks about "linking". I'm not sure what linking is about. I just want to create users. Is there a separate REST API for that? Also, please share the User schema. I would like to know what fields in the request are mandatory, what are optional and what are read-only (e.g. id field of a user can't be updated).

I'm looking to do the following operations on Users.

1. Create a User (POST)

2. Update a User (PUT or Replace, PATCH or selective update)

3. DELETE a User (DELETE)

4. GET A User (GET)

5. GET All Users (GET)

6. GET All Users with Pagination. Like only 100 records at a time.

7. Filter Users with some criteria. First Name, Last Name, User Name, Email Address, etc.,