Re: please help - paint newbie
Looks like a lot of work.
The marks/'corrosion' on the bottom might be simply from dirty travellift straps - in any event they'll clean up easily enough.
More concerning is picture #3 (damage to the green topsides)... looks like puncture holes and severe dock rash or worse. That's some serious f/g repair and fairing work required.
Is this a hurricane boat? Did water get inside? More work still if that's the case...
Judging by the fender rub (dark bruise in the green in another shot) I don't think this is any special sort of paint, but it does look like paint to me.
As far as what's there already, since you have no way of knowing you'll just have to try a sample of what you want to use next on a small area and see if there's any reaction/lifting or other reason not to use it further. But if you intend to repaint all the green topsides I think that paint has to come off, so that you can start fresh.
Best of luck...
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)