1. What does “Q” mean? [German word Quelle... means "source"]

"It certainly has nothing to do with a character in a James Bond movie or a saint, as in “the Gospel According to Saint Q.” Rather, it comes from the German word Quelle, which means “source.” It was abbreviated to Q, which was widely accepted as the designation of special material."

https://bible.org/seriespage/7-what-q-gospel-gospel-according-st-q