Thanks for your questions and I hope these answers go some way to helping you!
Jesus needs to come back to earth for several reasons. I have tried to encapsulate these in some verses.
Heb 9:28 to bring salvation to those who are waiting for him
2 Peter 3:10 But the day of the Lord will come like a thief. The heavens will disappear with a roar; the elements will be destroyed by fire, and the earth and everything in it will be laid bare.
1 Thessalonians 4:16-17 For the Lord himself will come down from heaven, with a loud command, with the voice of the archangel and with the trumpet call of God, and the dead in Christ will rise first. 17 After that, we who are still alive and are left will be caught up together with them in the clouds to meet the Lord in the air. And so we will be with the Lord forever.
I take it that more than fulfilling prophecy he will come to gather both the living and the dead and take them to be with him. It will also be a day when Jesus as judge of the world will see to its final redemption through fire and then the ushering in of the New Kingdom will come as is pictured in Revelation 21:1-6.
The question of free will is a difficult one to answer in a complete way in confined space.
If I can be specific to your question, I would say, is there any will that is not free? How can we be said to make a choice, if we were never free to make a differnet choice??
The way that different situations are all put in the BIble shows us the complementary position between our free will and God’s sovereignty. The classic examples I often ponder are Pharoah in Exodus 8:32 and 9:12 and then the rulers and people of Israel in Acts 4.
Acts 4:27-28 27 Indeed Herod and Pontius Pilate met together with the Gentiles and the people of Israel in this city to conspire against your holy servant Jesus, whom you anointed. 28 They did what your power and will had decided beforehand should happen.
There is a dynamic there in which God’s hand is over all things and yet, his plan is executed by the free will of those people involved.
I have always taken a position of humility at this and decided that the Bible writers were not fools who could not see the tension and that God would not have put the tension there if it were not something to hold in tension. Both the freedom of God and the freedom of man must be held as true in a way that we may not fathom now but that we will fathom when we know him face to face.
Please fell free to follow up.