Panama has a very good transportation system. There are numerous cabs. They are supposed to charge by zone ranging from $1.25 - $5.00. But watch out, they will try and charge tourists more. Fares in the main area of the city are about $2.50. A ride to Amador $5.00. Uber also exists in the city. The subway system called metro is $.35. You can buy a card in the stations. Cardcost $2.00 then you just add as much money as you need. As. far as travel outside the city the main bus station is at Albrook which is one end of the Metro train. From there you can take a busanywhere the country and farther for very reasonable rates.
You rarely see any Diablo Rojos (painted school buses) in town anymore. 
Or you can rent a bike and ride around Casco Viejo