If you use the buttons a fair bit then the battery will drain MUCH more quickly due to the power needed to light up the display.
As for getting the Sansa to navigate by directory, I wanted to do the same thing. After playing around a bit I found that I could put directories under the “Record” directory on the internal memory to more easily navigate to my podcasts. I haven’t had a chance to test out all the features with it, so not sure if the Sansa Express includes files in the Record directory when playing Random, but it does NOT like having more than one level of directory under “Record”.
