I swear that it is okay to swear...when the occasion calls for it. And that occasion is when it fits into a sentance without being gratuitous. Uhhh...you know what I mean. Anyway...
{1} You know, when you get down to it, I suppose there isn't much more of a real reason beyond adults hating the idea of their ten-year-old kid telling 'em to fuck off. After all, the little buggers are suppose to be kept in line and if they don't do it, then adults get pissed. To me, it doesn't often matter. I don't have kids and I don't curse around them. So, if I hear a kid shout "Goddamn it!", it wasn't MY fault.
{2} Answer: Hell no! There's a right place for these things. Swear for emphasis, to point out that you're not just pissed off, but royally ticked. Swear when you smash your thumb in the door because - Be honest. - it's the first thing to come to mind. Swear when something shocking hits your doorstep because you need to broadcast the fact that this is a very bad thing. These pointed words are warning lights, things people should pay attention to. They serve a function.
{3} Again, no. Not by profanity for its own sake. Weaponized profanity is different. That's when it's fired at you specifically as an insult. They don't call it the F-Bomb for nothing. SO, being sworn AT is not the same because you're not angry at the profanity, but that some jackass called you an asshole. Ya follow?