NX manufacturing

In NX
When I tried to set up "MCS_Mill", what is the "Avoidance", is it the same as "Retract plane"? What are the "from/start/return/go home point" under the "Avoidance"?
What is the "lower limit plane"?

In drilling operation,
When I was trying to pick the holes, what are the "Cycle Parameter Set - 1/2/3...", "Generic Point".
How can I set the dwell time? And how to set " 1'' shift ", and what does this "shift" means ?

Thanks a lot
Please help if you know the answer to any questions above.