Not Sure how to go about this

[nilamo]

As well as check their passwords and see if they meet policy

Passwords (even in the /etc/passwd file) are one-way hashes of the passwords.  You can't check if they meet policy, because you can't reverse them to the actual password.  If you could check them against policy, that would defeat the entire purpose of a password.  Would you CAN do, though, is setup a password changing tool that enforced policy, and then force everyone to change their password using the tool.