Semicolons

Q. My question is about the proper use of semicolons. My editor wants me to use the following construct when I use “that is” or “for example”: “You can tailor much of the desktop environment; for example, the background window.”

Q. Is the use of semicolons in the following series warranted (i.e., when the commas appear in the last member of the series and there’s no real threat of misreading)? It just looks weird to me: They were hunter-gatherers who sustained themselves by hunting; fishing; and gathering roots, berries, and various wild plants.