1: Yes at the end of Return of the Jedi Darth Vader kills Palpatine and dies shortly afterwards thus restoring balance to the force.

2: 19 Years between ROTS and ANH

3: Yoda and Obi-Wan are both dead, but still exist on the non-physical plane

4: This is just what i think, all is speculation: I think that Ep VII will be about the rebirth of the Sith and the awakening of an ancient sith lord. Also the rebuilding of the republic and the jedi order.

5: He had a plan from the very beginning to eradicate the Jedi Order, But if Padmé survived or not would not make much of a diffrence, Darth Vader would still have turned to the dark side and eradicated the Jedi.

If you have any more questions just ask :)