Some confusion about the rules

As this was my first gamejam experience, I encountered some ambiguity with the guidelines, and I did not find the corresponding explanation on the official rules page... I want to know:

  1. I noticed that everyone kept very few themes in the theme slaughter round. How is it determined which themes advance to the final round? Are the least slaughtered themes selected for the final round?

  2. I've learned that the game doesn't have to be strongly related to the theme. Can the game be completely irrelevant to the theme? For example, the theme is "limited space" and the game is an open world adventure.

  3. If I already have a good idea, can I write the general framework and core gameplay of the game before the game starts?

  4. (This is the limit case for 2 and 3, which may sound rather crazy) If the answer to both 2 and 3 is "yes", is there a game that can be released on gamejam that is completely pre-made? When I looked at the ratings, it seemed like a game like this could easily get a high score in all the other categories except for a low score on the theme.