ONE - Don't worry too much about the moisture and density of Specialty green coffee.
Specialty green coffee is selected for its quality and flavour. Good quality green coffees are required to keep moisture content within an acceptable range. For Specialty coffee, Specialty Coffee Association standard for moisture is 10-12%. Since the Specialty Coffee industry demands higher quality coffee, rarely does green coffee fall out of this range.
Acidity is one of the major factors that contribute to the desirable flavours in Specialty Coffee. Since the level of acidity in a given coffee is closely related to its density (higher density generally has higher acidity), Specialty green coffee has a higher density. The majority of Specialty green coffee falls within a narrow enough range that its impact on the roasting process will not be huge.
TWO - Don't worry too much about your charge temperature.
Five to ten-degree Celsius changes in the charge temperature will not greatly influence your roast profile. It is more important that your preheating and charge temperature is consistent between batches rather than its actual temperature. Actually, your protocol between batches of roasts as well as how you preheat to your charge temperature will have a greater impact on the heat within your roasting environment than what temperature you choose to charge your coffee. A simple method is to charge at the same temperature as your first crack temperature.
THREE - Don't worry too much about changing your airflow during your roast.
Airflow is an essential part of roasting. It is important that enough airflow is set for your specific roasting set-up and equipment. This means that you have enough airflow to remove chaff and smoke from your roasting drum. (A simple lighter test will help you establish this.) Once you have enough airflow in your roaster, just leave it. There are a lot of variables within the roasting system that causes unpredictable changes during your roast. If you are a beginner, trying to take control of basic functions and roast to your desired profile will be challenging.
The main method of controlling heat in a drum roaster is through the heat source. At the start of your roasting journey, you should focus on understanding and controlling your heat source. Changing the heat source as well as the airflow will add another variable that will make it even more challenging to predict and control your roast profile. (The only exception is if your roasting machine does not have adequate control of your heat source and needs airflow to compensate for your heat source control.)
As you begin your roasting journey, you may find it challenging at times to get the roast profile you want. Your roaster may be acting like a wild stallion and controlling it can seem almost impossible. This happens to everyone. Keep calm, keep it simple and don't give up!