If you would like to get a nice overview over Oslo combined with useful information given by a local guide, you should consider a guided tour, a sightseeing tour. There are several options to choose between, such as Oslo full day tours, Munch tours, walking tours and bus tours. We do not arrange such guided tour ourselves currently, but we can warmly recommend the services and guided tours of our friends over at Viator.
Check out their webpages at www.viator.com
A guided tour in Oslo with a private guide will make your stay in Oslo even more interesting and you will also get an answer to all your questions (hopefully)!