Lets educate and move on. Washing mouths out with soap is not the issue OP has. It is swearing and aggression.
OP maybe try ignoring some of his swearing and telling him if he must swear then do it in his room where no one can hear him. Explain how its not nice etc..
As for behaviour, I think you might need to set more firm boundaries and clear consequences such as time outs and confiscations as well as possibly look at his diet as well. My dd1 was quite aggressive as a toddler and things improved dramatically when we removed artificial colours from her diet.