1. If I have a notebook that is not always connected to the local network I use a shortcut on the desktop to connect the user to a mapped drive so Windows does not try to connect to it durring logon when the user is not on the local network. You can drag the icon from the mapped drive window address bar to the desktop and it will create a shortcut for you.
2. Forget the user name and password in the bat file. Create a user with the same name and password on the file server used to login to the workstation and give that user access only to the folder you want to map the drive to.