Looking at that third picture, I think you maybe in for more than you bargained for. That rust looks like it's extends further under the paint, and you may find some big chips coming off. Also you will get some pitting when you sand it down, so you will have to use a filler to get a smooth finish if you decide to repaint it.
I'm still trying to figure out what the previous owner was trying to do here, though. Did they want to paint the cable guide black, for some reason?