How long to bicycle from Hamburg to Dresden, Germany?

I am planning a June trip to Germany. I'd like to fly into Hamburg and bicycle in two days to Dresden. How far is the bicycle trail from the airport? Cycling laws and regulations? Night riding allowed?
Any helpful information would be greatly appreciated.
(I have ridden 175 miles [282 km] in one day recently)

The distance between those cities is 377 km on a straight line, so I think a bike trip along the Elbe river would be something like 500km. So if you're really making 282km a day you could make it.
No special regulations for bikes. You have to ride the bikepath if there is one, else you can ride on the street. At night you must have a light, which would make sense anyway if you're going overland.
Here's a website with some informations about bike trips along the Elbe river: http://www.elberadweg.de. It's partly in English. Get a good map and check the route before, so that you won't lose much time on the road with navigation.
So with some preparation and if you're fit enough, you might make it in two days.

But why on earth would you want to do that????

There are a lot of beautiful places along the road: old cities Hitzacker and Boizenburg. Dessau one of the birthplace of Bauhaus art and architechture. Wittenberg, where Luther started the reformation, with a bunch of historic sites. That's just to name a few places. If you plan to go all the way from Hamburg to Dresden by bike, then why not take your time to enjoy the beauties of this ride. It would be a pity to race through that in just two days.

+ I would give myself at least 3 days, if you want to push it. I think you need to take the hills into consideration. For a leisurely cycle add another day and have a couple of beers. You best be in good shape with good equipment or don't even bother. See map-quest below.

Good Luck