Been there twice...
Money exchange is on your immediate left, as you pass through the last of customs/immigration, right across the room, from the baggage carousel.
As usual in Cuba, it is one at a time thru immigration, unless your child is on your passport, or very young.
Smokers, will be happy to know, that you can light up, as soon as you walk into the terminal building.
Duty free is located in the departures area, and there is lots there. Prices are not too bad either. There is a VIP lounge in departures, but we found the "common folk" lounge to be just fine for us.
Re VIP on departures... Don't book it through the rep at the hotel. If the airport isn't busy, it's not worth it. Because it wasn't busy, and we had a "small child" with us, the airport guy pushed us into the VIP line anyway.