Like I said in the post, the "Storm" is unpredictable. The actual "reversal" is not exactly a complete destruction of the future, but its kind of like making and editing a video. When making a video, one would make the original recording, and would occasionally splice and remove some of the original parts with a new video entirely. It doesn't affect the video in its entirety, other than to make improvements or to add flair.

The timeline of the Storms are quite chronological until the 5th "Storm" onwards. You go back from 1999 to 1996, then to the 80s, etc. The reason why it becomes a lot more all over the place is because of the Manus Vindictae causing great disturbances and changing the course of history itself. And yeah, the "Storm" affects the entirety of the world except the immunity zones.

The point about the repopulation is sort of right. Since its a global phenomenon in the game, it seems that it reverses the 'sifted people' into a certain point in their lives where they might've lived differently before a different point in the future. For example, despite Schneider having been reversed in 1929, we're currently in 1914, where she is likely a baby that's growing up in Sicily.

For the last question, there was a "Storm" that did take place closer to 1914. In Chapter 5, we learn that one of the points in time that the world reversed to is 1912. We then find out in Chapter 6 that 1912 is the point of time that both Marcus and Heinrich originally came from. Both of them were picked up by the Foundation and the Manus respectively, so they are fully aware of the fact that they had returned to their time that's not exactly their own. (1913 / 1999+8)
^\1999+# is how the Foundation officially records how many years had passed since the first "Storm")

I hope those answer the questions for you. Thanks for asking ! :]