1. It just depends on the disease. If it was the disease then it wouldn't have been developed unless somebody coughs or sneezes on you. Or ext.
2. The main signs and symptoms of the disease. The main signs is when you cough a lot, or you are having trouble breathing. Pain in the chest, inability to wake up or stay awake, bluish lips or face, new lost or of taste or smell. Those are the main signs and symptoms. Though there are a lot more.
3. What age group is most affected by the condition?
The older people are. Example; 50s, 60s, 70s, and 85s.
4. How long does it last? Does it ever go away, or is it permanent?
If you take the right steps of quarantining yourself (not talking to your friends physically or family members). Then it will most likely go away, but you have to take great care of yourself. If not then it will either get worse. It will go away soon.
5. Is there a cure or treatment?
No, there is none of those at this very moment. Hopefully in the future there will be a cure or treatment. But for now we should take careful steps. At least meet your friends but social distance and wear a mask if so.
I hope I helped. Stay safe, and hope you have a nice day.