travel in germany

hi, i m going to travel in germany during end of december till early january 2010, planning to go for few cities in germany such as cologne, berlin, dresden, munich, stuttgard, heidelberg, mennheim and back to cologne (going around germany from north to south)
anyone know how much time needed to travel between the cities(by train)
by using german rail pass or any other suggestion?
any extra charges for luggages? if yes how they charge?

planning to go for few cities in germany such as cologne, berlin, dresden, munich, stuttgard, heidelberg, mennheim and back to cologne (going around germany from north to south)

You should plan on having around 3 weeks for such a trip, Berlin and Munich alone take about 5 days to see properly.

anyone know how much time needed to travel between the cities(by train)

http://reiseauskunft.bahn.de/bin/query.exe/en will tell you.

Berlin-Munich and Berlin-Cologne is best done with a night train or flying.

If you go Berlin-Dresden-Munich it can be a good idea to go Berlin-Dresden-Prague-Munich.

by using german rail pass or any other suggestion?

If you are very organised you can book trains in advance, thus getting special offers. This can work out cheaper than using the German rail pass.

Alternatives to using the train can be renting a car and flying.