Thank you very much for this article. It's the perfect guide about ZIP files and 7-Zip to share with friends.
An interesting thing to add at the end would be about the "Store" compression level. Lots of times I use this one, since my aim is to split, encrypt, or just store together a bunch of files, and I don't care about compression or it would take a long time. For instance, copying thousands of small (< 100 KB) JPG files to a USB drive can take ages. But storing all of them inside a single ZIP or 7Z archive makes the transfer speed much faster. Enabling compression won't do a thing, as JPG files are hard to compress losslessly, so I just choose "Store" to save time and resources.