Carpooling in Sweden

Is carpooling and cost-sharing common practice in Sweden? What about the regulations in force?

It exists but it is not a common practice. Private individuals seems to have economic associations and companies who run carpooling as a business have different other organizational structures.     

For which types of journey does carpooling seem more suitable in Sweden? How much is the cost of a carpool trip?

It's hard to know which types of journeys carpooling is more suitable for, however all carpooling have started from big cities where it is hard to find parking and it is very expensive to have a parking, so what I understood is it is more the maintaining part carpooling people wish to get rid of or wish to share it to have a low cost. I checked how much it may can cost on your behalf and there are different concepts from different carpooling and most common one is you have to pay a monthly membership whether you use it or not and then also for using hours, mileage and it also depends on what type of a vehicle. What included is insurance, tax and fuel and all other maintenance.   

  Is there an app or other means available to connect people looking to carpool? How do you find other carpoolers?       

Few of carpooling companies have their own apps and probably private individuals have facebook groups and other social media groups. I think that also could be a reason to be a carpooler, making new contacts through it.   

If you are carpooling in Sweden, what precautions should you take to travel safely?
Maybe insert into mind that always to drive on the right side...

According to you, what are the advantages and disadvantages of carpooling?

I don't see any advantages in a country like Sweden, few big cities and they are not really big either and great public transportation, when you really need a car once in a while you can rent one cheaper than for carpooling cost. And if you live outside the city area you hardly can survive without your own vehicle in winter time, carpooling becomes only a joke then.