Some notes on NordicFrosts comprehensive guide:

Cabs: What's stated in the writeup is correct. Do not, though, wait for a cab in the designated lines, walk directly to one of the larger roads and get one of the plentiful cabs that's heading back into town from rides. The driver will be happy to avoid the hassle of the cab stops and you will too.

Tønsberg: Be aware indeed.

Oslo: The prices in bars varies wildly, do your research and save a fortune.

When in Rome, do as the Romans: Drink at home until you're all out, then go out.

And last, but not mentioned: Getting drunk in Norway is quite fun! The tolerance for drunken behaviour is almost limitless, going out in the big cities is quite safe compared to other European cities and there will certainly be a party at whatever bar you choose.