Forum:Idea: Shoemaker-Levy 9 hits Earth

So I thought of the great idea of what would happen if Shoemaker-Levy 9, instead of hitting Jupiter, broke into 22 fragments and then (Some) hit Earth. This has been done, in a very limited form, here already: http://althistory.wikia.com/wiki/The_Wrath_of_Shoemaker-Levy?cb=3440, however I plan on going into much more detail.

I will start with a quick draft timeline that assumes it is four years between the calculated "99.8% chance of at least one fragment hitting earth" accouncement until Earth is hit. This is likely an incorrect amount of time.

Chapter 1
14th June 1994 - Despite predictions, a recalculation reveals that only some of the fragments will hit Jupiter, and the others will be gravitationally sling-shotted in a currently unknown direction.

26th June 1994 - Comet slingshot tragectory roughtly predicted, should enter the inner solar system some time in 1998

12th July 1994 - New estimates suggest there is a chance it might impact Earth. Media causes a minor panic over this.

13th July 1994 - More scientists begin work on figuring out its trajectory, and come to the conclusion that it is a possibility. Media continues to cause minor panic.

14th July 1994 - Latest predictions put chance of at least one fragment impacting at 45%. Minor panic escalates into major panic. Riots happen in several capital cities.

July - September 1994 - Predicted chance of impact continues to rise. Riots get worse, mass suicide of 19,000 occurs in New York.

29th September 1994 - Worst prediction so far, 99.6% chance of at least one impact. Riots turn into Anarchy in several nations.

30th September 1994 - Protesters worldwide take over 3 major cities, Chicago, Manchester and Stockholm. Military forces intervene, many innocents killed.

2nd October 1994 - Protests become even worse, Civil wars break out across Central Europe.

5th October 1994 - Yugoslav wars reach a peak in ferocity, resulting in massive devastation across the region. The existing nations there break into about 60 tiny nations.

6th October 1994 - The First Panic Wars begins, with wars being declared all over Africa.

October 1994 - April 1995 - The First Panic Wars. This series of conflicts start with almost every nation in africa declaring war on neighbors, and quickly escalates into skirmishes happening along every border, and within nations. In March, the USA, Russia, Germany, Canada and Australia all collapse into several new states, which continue collapsing into even smaller states. Many other new countries formed from various revolutions. The First Panic Wars end when North Korea nukes the West Coast Collaboration, a nation that was formerly part of the USA. This event shocked the arguing territories into quickly creating piece treaties. Despite the violence and inhumanity in the Nuclear Attack, North Korea likely prevented The First Panic Wars from continuing until 1998.

23rd April 1995 - Some divided countries manage to partially reform and merge, as collaborative attempts to build bunkers to try and protect as much of the population as possible occur. Before The First Panic Wars, the global total number of nations was almost 200, it now stands at 493.

Chapter 2
April 24th 1995 - The ISS Expansion Project begins, with the Official US Remnant (The areas of the USA still loyal to the government in Washington DC) head the project, which involves ultra-rapid expansion of the ISS into something that can repopulate humanity if every Human gets killed. The project begins with the attachment of the Emergency Thruster module, which is designed to move the whole ISS out the way of an incoming fragment of Shoemaker-Levy 9.

1st May May 1995 - Despite dedication, the project fails to get far. It does give the ISS a massive library of Scientific and technological information, but little else is achieved.

June 5th 1995 - An Official US Remnant Astronaut is murdered by a Northlake Territory Astronaut over a disagreement about what people should be chosen to stay on the ISS.

June 7th 1995 - Espionage reveals that both the US Remnant and the Northlake Territory aimed to only have their astronauts on the ISS when Shoemaker-Levy 9 hits.

June 8th 1995 - Eastern USA decends into war, as many nations declare war on eachover over the diplomatic mess. The Second Panic Wars begin.

May 1995 - November 1997 - The Second Panic Wars. The world quickly divided itself into several groups based on who they feel should be on the ISS. Wars between these groups happen, and limited nuclear exchanges (11 Nukes in total) occur within Former Russia, the former US, and southern India. On the 4t July 1995 a small Nation located in the south of former Italy deliberately crashed a satellite into the ISS, destroying it. Eventuly, civilians in every nation begin rebelling, and countries are divided into even smaller territories. The war finaly ends in November 1997 as piece treaties are scrambled together to prevent futher rioting, and because of the bankruptcy of almost every nation. At this point, there are about 1,600 nations in the world.

Chapter 3
November 1997 - August 1998 - The Last Peace. At this point every nation on Earth was battered to the point where it was no longer capable of fighting. Out of resources, out of people, and out of spirit, even if a nation had the things it needed to win, nobody even tried fighting. With the last scraps of money, new bunkers were built, with the goal of at least having a few hundred people from your nation survive.

August 16th 1998 - The Final Prediction was made on this day. It predicted the exact points where each fragment of Shoemaker-Levy 9 would land. For people living in the areas near these locations, dread and envy set in.

August 17th 1998 - September 2nd 1998 - "The Third Panic Wars" or "All or Noting Wars" or "The Last Bloodshed". Nations that were unlucky enough to be near where the fragments would hit entered an insane blood lust. Jealous of the land of people further away from the future impact site, they knew their only way to survive would be to invade the territory further away. Rings of front lines travel outwards from the predicted impact sites, as nations invaded the ones further away, they themselves were being invaded by the ones that were closer. Even with no resources available, people killed each other with stones, or with fists.

September 3rd 1998 - The first few fragments hit, about 2.3 Billion people still alive.

September 4th 1998 - Another few fragments hit, about 0.5 Billion people still alive.

September 5th 1998 - Bombardments stops

What I need help with
1. How many fragments will need to hit to reduce the global population to about 500,000,000?

2. How long would it take for the fragments to reach earth?

3. Are there any parts of the timeline which are too absurd?