I didn't think that TiVos needed to be put into standby mode, right? It doesn't affect the power consumption and recording, so...

In your device setup, you might have "never power off device" (or something to that effect) checked. I know I have it checked with mine because I don't want to put my TiVo into standby.

Regarding the previous channel...I assume you checked out the "customize button" screen? That screen has been the answer to all my button-mapping questions!