Arriving at OSLO through the DFDS cruise line is probably the best way. We had taken Crown of Scandinavia and had partied the whole night in the cruise and just after a royal buffet breakfast arrived at OSLO. If you have time, the dream come true trip will be to reach Bergen and from there take the Huritgen (my spelling is not correct, it is too difficult for me to remember) cruise lines and reach Tromse and come back. You will cruise between the Fjords and they are mind blowing.

In what month is best for a visit to Oslo?

may not be cheap, but the people are top notch. They are really friendly warm people and I always made feel at home when I visit

In Norway, the highly developed choral art. Who in Oslo is the most famous and popular conductor of the choir? :-)