Everyone recognizes a roasted coffee bean but unless you have lived or traveled in a coffee growing country, you might not recognize an actual coffee tree.   Pruned short in cultivation, but capable of growing more than 30 feet high, a coffee tree is covered with dark-green, waxy leaves growing opposite each other in pairs.  Coffee cherries grow along the tree's branches.  It takes nearly a year for a cherry to mature after the flowering of the fragrant, white blossoms.  Because it grows in a continuous cycle, it is not unusual to see flowers, green fruit and ripe fruit simultaneously on a single tree. The trees can live as long as 20 - 30 years and are capable of growing in a wide range of climates, as long as there is no harsh fluctuation in temperature.  Optimally, they prefer a rich soil and mild temperatures, with frequent rain and shaded sun.    Source: NCA 2014


There is no difference in hot air vs drum roasted. With the exception that hot air will provide a cleaner tasting roast sometimes, it depends on the size of the system.

Roasting is a drying process only if conducted within a 15min windows, otherwise your baking the coffee and that will not work.  Hot air vs Drum roasted, similar results.    Source: Mile High Roasters, 2015