We have tried to add in as much information as possible on the "Travel" page. If you still have any questions, feel free to reach out to us!
You can reserve the hotel we recommended - Hotel Viaggio in El Poblado - at least for Saturday and Sunday (the day of the wedding) so we can all spend the most time together! The cost of the hotel for double room with our special discount code should be around $60 - see "Travel" tab for the link. Also the Meet & Greet event and pick up to go to the wedding will take place at the same hotel. If you prefer to stay somewhere else, you can choose the accommodation through Airbnb or Booking but El Poblado is highly recommended area of Medellin.
The currency they use in Colombia is Colombian peso. 1 USD = 3,765 pesos/ 1 EUR = 4,156 pesos . I would recommend to withdraw cash from the ATM, as many exchange companies will offer you not very convenient rate.