Clarification of dates and times for XYM

Are there actual specific dates and times for the XYM transitions?

That is

[1] When does the snapshot actually stop/end, eg 7 daya before the XYM launch or a few days? How will we know?

[2] What is the exact time of the XYM lanch or block height, and how will we know?

[3] I am a bit unclear when the snapshot ends exactly.

[4] If after the optin/snapshot ends, I move my xem from the signalling wallet to another wallet will I still recieve the XYM OR does my NEM need to remain in the signalling wallet until main net launch?