Sentry 2.0 Phone Call Blocker

Is it possible to turn off the new "auto save to whitelist" advanced feature so it is a pure whitelist blocker?

If a new caller presses zero will he be able to leave a message on my answering machine?

Any products with - contacts go through, non contacts go to answering machine, blocked #'s get hung up on?

Versions 1 and 2 look alike. How does one tell the difference between these 2 units? Is there a model number or version # printed on the units?