Not speaking Spanish will not be a problem. You should be fine.
Do a quick search on here, you will find a couple options. We used My Friend Mario. Others have recommended a service "Your Man in Panama"
While it is a bit more than a standard taxi, the small difference is worth having someone meet you at the airport.
When you use taxis in Panama, do not use the ones at the hotel. Way more expensive. Most rides around the city should just be a few dollars.