Please be aware that "Policies" in alfresco already has a meaning different from the way you use it in the first posting.
Each document in alfresco has its own access control list and in addition authorities may (or may not,if that's the way you want it) be "inherited" from the folder that contains the document.
Aspects do not control security directly but you could have an alfresco policy that changes the access control based upon the aspects.
I think you are describing a "role" of which there are a couple in alfresco, for example for RM, however I suggest that first you understand how to use normal alfresco security.
The system is very flexible and configurable and should you need to delve in then there are options, but that's no a first step.