1. yes
2. Yes
3, yes but you have to pay duty on them that is around 50-100% of their value and you’ll need someone’s tax ID number (CUIL) to pay for it.
Though it is my understanding that it is best to revise the marriage certificate once you get the DNI. If you need to prove the marriage while in Argentina years later your DNI number will be the same, but you foreign passport will not.