1) Delete pre-loaded music.
There are two ways. 1 is to do a hard reset and delete by pressing and holding the Back Button and the Up Button, when the units resets continue to hold the Back button, and all your content will be deleted.
Furthermore, you can simply go to the Zune software and go to Settings > Device > Erase Content this will also remove all the content on your Zune.
2) Can I set the display to show the song title and art, no album art?
I am not aware of an actual option for this anywhere in the software or on the hardware, but I know of a hack to accomplish this. Simply go through each of your albums folders and delete the album art. Then it won't sync to your Zune and display. Although I honestly can't imagine why you would want to do that. Feel free to share.
3) Zune is currently only enabled to work in landscape mode when viewing videos.
Hope these help!