Do I need to use a tamp if using a Moka pot stove top espresso maker? Can I just add the coffee powder to the basket and let the the water vapour do the work or should I make use of a tamp same as with a professional Espresso machine?
You should not tamp the coffee in a Moka. These pots don't like excessive pressure, which tamping would produce due to increased density. This is also why the water should not cover the steam valve. In the worst case they can literally explode!