Formal attire ~ bright colors are encouraged! Tuxes, suits, and gowns are all welcome. The reception is outdoors and has a gravel soil, so please keep this in mind for your shoe selections.
If your RSVP includes a guest, then yes.
No, it is not necessary to have a car, the entire city 'centro' is pedestrian friendly. You can also get around by taxi. While a vehicle is helpful when visiting sites outside of the city, like Hierve el Agua, you can opt for a local car service to drive you to farther destinations. Should you want transportation from point A to point B within the downtown, cabs are readily available. To get to and from the airport, you can take a taxi, bus, or rental car. We do suggest scheduling a ride from the airport to where you are staying in the city at least 24 hrs in advance of you arrival.
The weather should be temperate climate with highs in the 80s and lows in the 60s.