Answer:
I can sizzle like bacon, I am made with an egg. I have plenty of backbone, but lack a good leg. I peel layers like onions, but still remain whole. I can be long, like a flagpole, yet fit in a hole.
Useful tool for who in darkness dwell. Within you, corrupting like a deadly spell.
We are five little objects of an everyday sort. You will find us all in a tennis court.
What can't you see, hear or feel, until its too late. What shadows love, and shopkeepers hate?
What contains zero calories, but if you consume it, you will probably gain weight?
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?