Yeah, the mirror part is tough since Poser does not have a ray tracing rendering engine. This means that you can't render reflections in a mirror. You can "cheat" by rendering the reflected image separately, saving it as a picture, making a mirror image of it in a picture editing software and applying it to the "mirror" as a texture. Walk can (relatively) easily be created in the Walk Designer, that is an integrated part of Poser 4. You will find a good description of it in the manual. Basicly you set a walk path, assign a walk "style" and let Poser animate it for you. Looks very realistic once it's done. Sitting down, standing up etc, is done with the basic animation functionality. You assign the basic poses you want and Posers animation feature will animate the motion in between these poses.