How does the Districts system work?

[gabrielau23]

Hi, I'm relatively new to FRC, and while competing in DC and Chesapeake, I heard rumblings that the MD/VA/DC area was moving to districts. At the same time, while monitoring Chief Delphi, I've noticed several threads on the subject of districts. So I have a few questions.
1. How does the district system work? (duh) Does that mean that only teams from within that district can compete against each other? If so, I'd be hesitant to move to districts. At DC, it was awesome to see teams from Brazil and Israel, as well as Florida, North Carolina, and so forth. Likewise, at Chesapeake, New York teams and some Pennsylvania teams were very fun to interact with.
2. How does the district system offer advantages over the Regionals system currently in place?
3. What are the complaints of the current Regional system?
4. What is a Super Regional? I can't imagine that it could only take winners from the districts, as you would need A LOT of districts to currently call a Super Regional "Super" when both the DC and Chesapeake comps are usually 60+ teams.
So I guess those are all my questions. Links, flowcharts, videos are all welcome.