San Juan is about 40 minutes from Rio Grande. If you prefer to stay in San Juan look into transportation options.
I recommend wearing something casual and light to rehearsal dinner. Dinner will be served outdoors next to the beach. Women think maxi dresses with sandals or wedges. Men think linen/khaki shorts or pants with polo or button up shirt.
The wedding and reception will be held outdoors. I recommend wearing garden attire. Women think bright colors or floral pattern dresses. There is uneven ground to walk on so block heels or wedges would be best. Men think light colored suits, tie optional.
Children are not invited to this event.
The weather in March on average is a high of 83F and low of 73F. There is a low chance of rain and the humidity is high.
Yes, Uber is available on the island. I have been told that in the Rio Grande area it is not as available in the evening. We will provide transportation from the Hyatt Grand Regency to the wedding venue and back. Rehearsal dinner will be held at the Hyatt Grand Regency on Sunday. If you plan to stay somewhere other than the Hyatt, I would look into transportation options.
No you do not need a passport.
Here is a link for information regarding travel to Puerto Rico https://www.discoverpuertorico.com/info/travel-guidelines. I recommend checking this often.