Jesse was the father of David.
We know that in the Millenium the Lord will change the chemistry of the animals so that they can eat different food (plants). I believe that this also teaches us that the Lord can change our internal parts, so that our sources of strength have changed, and also ends natural animosity that has existed between two peoples for the history of the world.
The Lord can change the physical attributes of the animals, so that their diet has changed. Also, in us, the Lord can change us internally, so we dwell upon a different feed and have the inward parts changed. See also Alma 60:23 - the Lord changes the inward vessel first.
The second gathering of Israel was the Restoration, the first gathering was when Moses gathered the tribes from Egypt. Remember that the Lord's kingdom is "not of this world" – it is not political, but spiritual.
Sets up a pattern, the order of things that will happen.
I don't think the envying will magically change overnight. Rather, I think the gospel of Christ, when taught, will naturally change their lives.
The Philistines were a sea-faring people. Them flying up on their shoulders means that the Lord will use the technologies of the day.
The highway is the ability to be gathered.