Yes. And, there are other possible expansions, e.g. Gates William.

This is likely no different than the MZ in the DOS exe header. Nobody actually knows (and says!) what MZ stands for, but it is believed to be Mark Zbikowski.

Pretty sure it is Mark Zbikowski.

I believe that, too. However, for something like a zip file, I KNOW that the PK in the header stands for Phil Katz.

To be fair, he did design the file format

Greg Whitten. I don't know the answer.

Whoops, yeah.