NO. All you need is your DL, vehicle registration and birth certificate. We recently stayed in Mexico and had no problem at the border.
No, you do not need to change money before going to Mexico. Cash and card are both accepted but cash is recommended for vendors (Hair braiding, Jet skis, ATV's, Massages, and Food vendors)
Most places accept visa but the vendors accept cash (jet skis, hair braiding, banana boats, vendor food and massages). Bring cash for fun activities and food for your family for the weekend. Dinner is held at La Curva on the day before the wedding (24th), dinner will only be provided for you on the wedding evening. The following day (26th), you have the option to purchase brunch for $23 a person, breakfast burritos $10, or you can go to Walmart, Sams Club, or Ley express grocery store and buy food and cook at the Villa. The kitchen is huge with 3 refrigerators and is fully equipped with everything you need to cook.
There are water bottles in the bathroom sinks for you to use when brushing your teeth. The tap water is not filtered the same as back home. So the water bottles remind us not to use tap. Bring a case.