Hi Brian,
I will try to answer some of these from things I’ve read in the forums and from some answers from the Q&A. Any answer I have is completely my own opinion/interpretation of the information.
- The 6 month slip was do to them completely redoing the schedule. The new schedule has additional slack built in for risk mitigation, so the schedule can slip to the left instead of to the right.
What that means to people who aren’t familiar with Microsoft Project (or other project management software), a slip right means you are missing a deadline and it is taking longer. A slip to the left means you are ahead of schedule.
So, they are hoping to get it delivered ahead of time, they just aren’t promising it in case there are other issues that pop up.
2&3) 
I don’t know.
I believe they stated that they had a drop dead date of a week or so prior to the delay announcement. When they hit that date, they had to decide on a new course of action and run it by their investors. So, up until that point, they had enough time to do testing and deliver, barring any other issues arising. It seems like they took the direction of delaying a lot up front and (potentially) delivering early instead of (potentially) having a lot of small incremental delays.
Hope that helps. 