I think I can answer a couple of these but someone else should jump in here and correct me if I'm wrong:
You can only control the tempo of the tracks from the "master" deck. Whichever deck is "master" at any given time is shown above the waveform, underneath the "sync" indicator.
When sync is on, and you want to control the tempo of the master deck, you have to move the pitch slider to where the tempo actually is on that deck before you move it to where you want. You'll see a little ghost indicator on the slider (on the screen) that shows where the pitch is on that track. This is kind of confusing to try to explain, haha!
I have no idea about the wild tempo thing.