How is security access determined? & How to view security model for user?

I have two questions

1) User A requests access to resource X. How exactly are the permissions determined? I can see many different scenarios for configuring security and I would like to know if there is any documentation on what exactly the order of execution is for checking permissions to a resource.

For example: 

1) Check privileges from the union of all roles assigned to user and roles assigned to team user is member of

2) Check shared records

3) ....

4) Final determination: User A has Read and Append access to record X

This is likely wrong but it illustrates what info I'm looking for.

2) Is there a view anywhere in the Dynamics CRM portal that I can see the security configuration for a single user i.e. all the records or entities a user has access to as well as records the user does not have access to. (Taking into account all of the users roles, team roles, ...etc.)