I am not sure if you already traveled.
For such a long stay you can consider getting a hotel room so you can shower and sleep a little.
lots of nice hotels
if you speak Portuguese slowly and enunciate every work clearly, most people will understand basic sentences.
Panama city is relatively safe.
this is a tour from the airport to the canal and the old part (casco viejo); it is expensive but may be worth it.
https://www.viator.com/tours/Panama-.../d950-39483P12