Answer:
Break it and it is better, immediately set and harder to break again.
I work when I play and play when I work.
Left to right I’m quite bright. Right to left I might bite.
I can be used to type and point you see. But don't forget, you can count on me. What am I?
What contains zero calories, but if you consume it, you will probably gain weight?
I’m grown from darkness but shine with a pale light. Very round I am and always a lady's delight.