Q1 - Here in the classifieds section, Ebay, scrap yards or specialist scrappies, other VW forums and anywhere else that brake cars.
Q2 - You could, but its alot more work, would need to uprate brakes, suspension, etc etc................not worth it imo
Q3 - If you get it from a breaker/scrap yard then possibly, you would need to ask them.
Q4 - Corrado G60 is hard to come by anyway, but a Golf G60 is very very rare if not a conversion anyway.