Re. the black paint; you don't necessarily have to remove it - if it's flaked off in places already, chances are that it's merely a 'shipping' primer, intended to prevent flash rusting between production of the panel and it being properly finished. But some panels are cataphoretically coated (also known as e-coating), which has the same appearance but is electro-chemically applied to the panel and is an effective barrier to corrosion. To finish such a panel it is only necessary to key the surface to promote adhesion of the material you intend to apply. You could remove e-coat but, in theory, it will protect the panel just as well as, if not better than, any material you might apply instead - best to just use it as a good base to paint over.
Edit: I should add that, if you were to leave an e-coated panel unfinished, it will of course be more susceptible to stone chips and scratches than a panel with several layers of primer and top-coat, with it being just a single layer. And if we're talking about a Punto bonnet...we all know how prone they are to stone chips. Probably best to paint it ultimately, even if you stick with black.