1) If you don't have it enabled, it won't start automatically. I'm not sure on what you mean here.
2) If you press COMMAND+DEL (Mac) or CTRL+DEL (Win), it will remove the song from the automix playlist without requiring a confirmation dialog box.
3) Do you mean like the song is deleted from the automix after it's been played? The reason it doesn't is two-fold; one, to allow you to create a playlist from it (I know, you could do it from the history, but then you could simply keep this list in there any time you needed it), and two, to allow for a loop-back in case you run short on songs - it won't just stop.
4) No, since most DJs would be using rekordbox with a hardware controller, meaning any changes in the software would require a "pick-up."
5) Open the ZOOM controls on the left side of the waveform and click the - (minus) button; you'll see more waveform - the specific amount depends on the resolution of your display. If you want to see further, look at the overview waveform on the deck itself.