Coffee is best stored in an airtight container made of ceramic, glass or non-reactive metal. Higher quality prepackaged coffee usually has a one-way valve which prevents air from entering while allowing the coffee to release gases. Coffee freshness and flavor is preserved when it is stored away from moisture, heat, and light.The ability of coffee to absorb strong smells from food means that it should be kept away from such smells.Storage of coffee in refrigerators is not recommended due to the presence of moisture which can cause deterioration. Exterior walls of buildings which face the sun may heat the interior of a home, and this heat may damage coffee stored near such a wall. Heat from nearby ovens also harms stored coffee.
Source：Wikipedia

Over-cooking your coffee is one of the most common reasons your brew tastes bitter. Much like tea, coffee gets its flavor from steeping in hot water. If you let it steep for too long, too much of the bitter flavors come through and your coffee will taste burnt.

What acids are we talking about? In its pure state, green coffee contains a lot of different acids — good ones and bad ones. Some go away in the roasting process and others don’t, so roasting is all about finding the right balance in terms of acidity, aroma, and body.

Crema is a flavorful, aromatic, reddish-brown froth that rests on top of a shot of espresso. It is formed when air bubbles combine with fine-ground coffee's soluble oils. Some people refer to this as the "Guinness effect" because it mimics the head on a pour of the popular Irish stout.

Robusta coffee is coffee made from beans of the plant Coffea canephora, a sturdy species with low acidity and high bitterness. C. canephora beans, widely known by the synonym Coffea robusta, are used primarily in instant coffee, espresso, and as a filler in ground coffee blends. Robusta has its origins in central and western sub-Saharan Africa. It is easy to care for, has a greater crop yield, has almost double the amount of caffeine and more antioxidants, and is less susceptible to disease than arabica coffea. It represents up to approximately 40% of global coffee production, with arabica constituting the remainder.
Source：Wikipedia

It’s not a question of light or dark roast. Nope. The amount of caffeine is decided by the amount of coffee used when brewing.

Coffee percolators and automatic coffeemakers brew coffee using gravity. In an automatic coffeemaker, hot water drips onto coffee grounds that are held in a paper, plastic, or perforated metal coffee filter, allowing the water to seep through the ground coffee while extracting its oils and essences. The liquid drips through the coffee and the filter into a carafe or pot, and the spent grounds are retained in the filter.

Coffee is adaptability beverage, depend your flavor.