Automation

When I edit a Parameter and press Undo, to undo this parameter, why it stops the song?
In a new project after the last update it schemes to work or it works only sometimes?

Why I could not use some external midi controller to record a automation?

Why I could not use the full range of the right slider because the panel covers a part of the slider.

And why was this not covered in an older Cubasis 3.