You certainly have the right to say, "Excuse me, I'm working." If they are messing with your stuff, "Hey! Don't touch!" could be appropriate but, unless the other person is being an extreme pest or acting dangerously, cussing is not appropriate.
I generally like talking to other people while I am photographing but there are times when I am trying to get an important shot or when I am trying to concentrate on something when I don't want to be bothered. I haven't got a problem telling people so but I usually make an effort top go back and talk to the people afterward.
As to location, others have said the same things am thinking. Anybody has the right to shoot any photograph they want in a public place and you can't stop them. Most of the time, I don't worry about copycats. Ten different people could photograph the exact same scene from the exact location and come up with ten different photographs.
I have had a couple of occasions when I was pestered by idiot, copycats with iPhones and digicams. I took the opposites tack.
"Make sure you get that tree in the composition... Watch your exposure... Make sure you get that detail in the shadow but don't burn out the highlights..."
Most people get confused, fed up and just walk away.
It isn't cool to be rude but nobody said you can't be a stinker once in awhile!