Midarkai HaKetores

"Here you have a service more precious than all the others. It is the ketores incense that is more precious than all the korbanos, but a deadly poison has been placed within it."

Our rabbanim have recommended that we recite the Pitum Haketores daily during the recent (Covid-19) pandemic.

What is the source for this?
What are the benefits of saying the section of the Ketores?
Are there any specific halachos that relate to saying the Ketores?
What are the specific spices used in the Ketores?
What lessons are to be learned from the Ketores?