I would love to drive through Brazil and Suriname starting from French Guyana. However, renting a car to do this proved to be impossible. There are ferries between France and Suriname and a bridge between France and Brazil. This implies French registered car do cross the border to Brazil and Suriname. If I am not a resident of France, would I be able to buy a second hand car, insure it and cross the border to Brazil and or Suriname?
You ask many questions, and the answers are several.
Of course, it is mandatory to have insurance in France (and French Guyana), it might not be the case in Brazil or Surinam). If you have a very beat up car, you might not care that much.