Hi. I think it would be very difficult to sell photo's on line, these days everyone has a phone/camera, and the quality of photo's has much improved over the years. My friend who is a professional photographer has thousands of cat photographs that he used to sell, they were used in magazines, brochures, and calendars. No one wants them now as the technology has moved so far forward.
I sometimes get requests from people wanting to use my photo's. They find them on my blog and they are just what they have been looking for. I always give permission, it's nice that they ask, and it's too much hassle to ask for payment. I know some bloggers get miffed if their photo's are stolen and turn up on other sites.
Sorry can't answer your questions, but I also say, don't bother, unless you are prepared to look at it for the long term, build up a portfolio, build your reputation, it ain't going to happen overnight. You could always join the paparazzi brigade and scramble for a pitch outside the big celeb events. Good luck whatever you decide.