The biggest airport is frankfurt, I think you maybe know that, but this airport is big, so there is many traffic, I'm from Hamburg, the airport is the third biggest I think, the airport is very nice, the problem is, they are extending the airport.
So there is no rail-traffic to the airport till 2008.
You have to take the bus 10minutes to the next metro-station.
Germany is nice, well T&T too
, I think it is easy to get around, everything is out-discribed so there is no problem.
If it's better to rent a car or using public transportation, that's your decision, I mean de cars are in a good condition with all kind of extra stuff, but it is not cheap to rent a car in germany.
I can only tell you the prices of the public transportation for hamburg, there you have to pay 4.45euro, and you can use the metro in whole hamburg the whole day.
A group (to five people) have to pay 8euro.
Now, your last question, I would buy the tickets for the games in trinidad & tobago, because I think you won't get a ticket in germany, I'm sure, that they are sold out, when the World Cup starts.