1) Windows Server does not normally care the number of clients from which you are logged in, nor prevent or warn you when logging on to multiple times. If logging into a terminal server, the terminal server might be configured to only allow one session to a user, but I don't think you are talking about that. The only problem you might run into with the folder redirection is if you left a document open on another machine. Then you may be denied access to the document.
2) If you look at the properties of My Documents when redirection is working, it should show the target path. If the computer is not applying the policy correctly, you may want to run gpresult on the workstation and see if it tells you why it isn't applying the redirection policy.
3) Here are the basic complexity requirements for windows passwords. The password must contain characters from three of the following five categories:
* English uppercase characters (A through Z)
* English lowercase characters (a through z)
* Base 10 digits (0 through 9)
* Non-alphabetic characters (for example, !, $, #, %)
* A catch-all category of any Unicode character that does not fall under the previous four categories. This fifth category can be regionally specific.
Additionally, you may not use the entire username or full name of the account.
The administrator may also set length requirements.
4) 169.xx addresses are not assigned by DHCP. Rather, a machine will assign it's own 169.xxx address when it does not receive an address from any DHCP server.