Oslo travel tips

So I'm planning on going to Oslo for five days in early March, and I'm basically just trying to lurk around and check out the scene there. Mostly interested in hiking around some national parks (mountains and fjords n shit), going to one or two ski resorts, and checking out the art/music/bar scene around Oslo. If anyone is familiar with the area, I'd love to know the go to spots for these kinds of things. I'll be staying in Oslo each night, but I'm down to take day trips to places that are further away from the city (prolly don't want to drive more than about 4 hours away though). So if anyone has some suggestions, that'd be dope.