It is easiest to rent a car at the Monterrey airport and drive yourself. You can use your car to go to the hotel in San Pedro, to get around Monterrey and drive to the hotel in Saltillo. We will have shuttles between the hotels in Saltillo and the wedding venue.
The main roads and highways are overall very good condition- some side and country roads may not be in as nice of shape. Be sure to have some Mexican Pesos on you for the tolls and be aware for traffic conditions changing more quickly than you are used to in the US!
Easiest way is to use your bank card at one of the local ATMs- there are many ATMs at the major banks around San Pedro- Citi Banamex, Santander, Banregio, and BBVA among others.. Usually this will get you the best exchange rate with small fees.