US citizens receive a visa at the airport upon arrival to Panama, so you DO NOT need to apply for one before traveling. Important! You need to have a return ticket booked in order to get on your flight to Panama.
It is recommended that you get yellow fever and typhoid vaccinations. Malaria pills are optional, but Angie and I do not recommend them. They cause more trouble than they're worth. Malaria is not prevalent in the areas of Panama where the wedding nor other activities are planned.
$20-$35 would be a reasonable price for a regular yellow taxi, depending on where in the city you are going. In off-hours/days, you can Uber there for $15-$25.
Many Panamanians involved in the service industry speak basic to good english. However, if you're off the beaten path, you shouldn't expect to get by on English alone.
Tocumen International AIrport to Panama City: 30 mins Tocumen to wedding venue (Capira) 1 hr 20 mins Panama City to wedding venue: 50 mins. Panama City to Coronado (beaches): 1 hr 20 mins Coronado to wedding venue: 30 mins