Okay, I'm not a prophet, but I'll try my best to answer your questions.
God came to earth the first time, as written in Gensis when He created Adam and then Eve in the Garden of Eden.
God came to earth the second time through His Only Begotten Son, Christ Jesus.
When God comes to earth the third time it is what is called "The Rapture," "Armageddeon," "The End Times." Anyway, this is when Christ will return to earth. All people who have lived good lives and are still alive will be taken to Christ. The rest of us will remain behind for the "tribulation," which is when Satan gets to run amok in the world. (It is said this period will last seven years ... but that can be debated.) When those seven years are completed, a thousand year of peace will come. Christ will come back to defeat and bind Satan. After that, everyone goes to a different world. Some will go to be Satan because they were never baptized or believed in Christ. The rest will go to be with Heavenly Father.
I hope this helped.
Merry Meet and Merry Bide
Cheryl