Here is the guide to Stockholm on EasyExpat (http://www.easyexpat.com/en/stockholm.htm) which includes info on transport & other valuable info.

I was also able to find a lot of people complaining about the things you worry about. Expensive parking, low availability of parking, high insurance rates, congestion fees, etc. It seems like you need to weigh convenience with available funds. Will you live far outside the center or have small kids? This site, http://www.whatprice.co.uk/car/car-costs.html, offers a good guide to evaluating the costs associated with ownership.

As far as charges, there is:
Road tax (When it comes to road tax, if the car you buy is new it may be exempt from the road tax for the first 5 years of ownership, however the car must meet certain environmental criteria. )
Stockholm congestion charge - max SEK 60 per day, depending on how much you drive in to or out of the congestion zone, between the hours of 06:30-18:30 every weekday. However there is no congestion charge on red days, the day before red days or for the entire month of July
(If you have a bio/flexi fuel car you may be entitled to a complete exemption from the charge.)

I've found some people paying about 800-1.000 SEK per month for parking garages. The city offers a good guide to parking in the city here: http://www.stockholmparkering.se/engpar ... eneral.htm

Best of luck!