Transmission zero, poles-zeros, loaded/unloaded-Q

I am working on filter design and sometime get confused with some terminologies as follow:
1) What does actually mean by 'transmission zero'?
2) How do the 'poles-zeros' affect the response of a filter? What the importance of poles-zeros in this case?
3) What different between 'loaded-Q' and 'unloaded-Q'?

Could someone pls help to explain them or suggest reading materials that suitable for beginners or students.

Thank you