1

are you looking for campsites or building sites?

2

Typing error - meant to write sights as in sightseeing

3

You can see most of Duesseldorf's sights quite comfortably in one day. The Altstadt is an obvious place to start, other than that it's up to you to decide what sights you are most interested in yourself.

What I - having lived in Japan a few years - find particularly interesting is that Duesseldorf has a large Japanese expat community (around 7000 people, I've been told). Many Japanese businesses are found at Immermannstrasse, which has several good restaurants serving authentic Japanese food as well as Japanese supermarkets, bookstores etc. When I was in Duesseldorf two weeks ago, I had a great lunch of rāmen (noodle soup) and gyōza (dumplings) at Takumi for less than €15 in total. Make sure you get there by noon when it opens or be prepared to queue for a table, as it seems to be extremely popular among Japanese businessmen working in the area.

As for bars: even though I visited on a weekday night, the whole Altstadt was packed and many bars had put up tables on the pavement. We had a few beers at Zum Uerige (http://www.uerige.de/en/start/), quite touristy but the home-brewed beer tasted good. There are plenty of other bars in the area, but I honestly don't remember the names of the ones that I have been to during previous visits.

4

For having lunch go to the "Na Ni Wa". Na Ni Wa is my fave since it has a lot of choices... if you fancy noodle food you can go to Na Ni Wa noodles restaurant but if you like sushi go to the Na Ni Wa sushi restaurant in front of it. The price is really reasonable for Japanese restaurant.

5

I lived in Dusseldorf for three years. In the Altstadt be sure to check out Ratinger Strasse, which consists almost entirely of bars. Apart from that Bolker Strasse may be interesting.
If you are interested in architecture, do not miss Medienhafen - the famous Gehry buildings are to be found there and you can visit the observation deck on Rhein Turm for splendid views http://www.duesseldorf.de/touristik/bildarchiv/bilder/gehry_turm.jpg There are also some nice bars and resturants in this area.

6

There are many museums in Düsseldorf. The Gursky exhibition in the Kunstpalast is quiet interesting and next door is an interesting exhibition in the NRW Forum.
The bars in the Altstadt are nice, except from the Bolker Str.. Try Em Pöötzke, the Quetsche or the Schaukelstühlchen. Dancing is nice at Pretty Vacant Club.
If you are interested in vegetarian food I could recommend some great places to eat.
Have fun.