Quickened by the Spirit

Why did Nicodemus come to talk to Christ? Is there an exact time when someone is regenerated that can be pinpointed? Why did Christ perform miracles? Was Christ discouraging or scolding Nicodemus for coming to Him? What is it to be 'born again’? Did Nicodemus know Christ at this point in time and did Christ know him? What is the significance of the word ‘water' in the Scripture? What is 'revival preaching'? How is the blessing of the work of the Spirit given?