You can snag a sim card as soon as you land at the airpot- just ask them to check it to make sure it's working properly. I'd put some extra money on it for later incase you run out of data. The airport wifi is spotty unless they've been updating it.

Forget taxi's in Panama City - UBER is everywhere and it's cheap to cross the entire city in traffic won't be more than $9 and will work right out of the gate from your existing account. Most drivers speak some Spanish.

I've done NYE at Hard Rock Hotel a few years back, the club and the sky bar are cool spots.