How to manage Site, Sub-Site, Lists, List Attachments, Files and Directories with Powershell?

Question

I'm working on a script to load up a sharepoint from scratch with tons of useful data. one of the things i really need to do is assign sharepoint users, active directory groups, and sharepoint groups to the Sites, Sub-Sites, Lists, List Attachments, Files and Directories.

Can anyone show me an example of how to assign one or all of these things from Powershell? Not much in the way of examples out there right now.

Here is what I did find:

Add Group to library: Add group to Library permissions using powershell

Answer 1

Can you confirm for me that you basically are looking for powershell methods of applying permissions to various levels of the Object Model from the SPsite object down to an item level, including how to add SP GROUPS to a site and fill those with AD groups.