Accra is quite pleasant...... With regards to your quest for a car and accommodation why not seek advise from your local colleagues at the airport.
A bunch of great guys out there, have flown and hung out with a bunch of them. I'm sure they will be able to point you in the right direction.
Nothing wrong with a stroll across the ramp for a quick hello and howz it going guys....
Have a good time.......
Zazoo