Q: Is it possible for sellers to upload a description translation per each market?
A: The translations are automatic. Mercado Libre expects sellers to upload English text and it is then automatically translated into Spanish (Mexico, Colombia, Chile) or Portuguese (Brazil).
Q: Can a seller manage the exchange rate?
A: No, the currency exchange rates are determined automatically by Mercado Libre.
Q: Can a seller modify shipping fees?
A: No, the shipping rates are determined by DHL, it is not a value that can be modified by the seller. See details here.