Setting a printer password

I work in an office where there is a lot of personal data and credit information available on our computers. Recently we have had a few issues with fraud. I wondered if there is any possibility of if someone needs to do a screen print then there should be an alert box asking for a password to enable the print to continue. Can this be done under a local administor setting?
Also, when we press ctrl+alt+del it gives us a chance to lock our computers. If somebody does not do this it locks itself after 15 minutes. How can we reduce the automatic locking time?