Can you use a web cam as a security camera. Yawcam has the software.
But will it work?

Yes. There are plenty of tutorials on the web that explain how to do it. You may need a little tech savvy to get it done.

Yes, some will depend on the quality of the photo. Web cams vary in quality, mine would be great at 4 or 5 feet, not any good for other side of the room.