Hi,
I lurk here often, rarely commenting, but your post intrigued me. For some of your questions the answers are simple, for others I don't think there is a real answer.
A question you didn't ask, which interests many who have it, is "why do I have this fetish? How did it begin for me? How come you have it?". Most responses I have seen are typically, and perhaps predictably, Freudian: it was known about in each individual since infancy, childhood memories of food-play, falling in mud, television from the nineteen eighties; gunge-filled gameshows featuring ritual humiliation.
The thing about this fetish, or at least this scene, is that it is made of people with very diverse kinks. What does it for one person does nothing for another. The lowest common denominator is that for everyone here something wet and messy is involved. I guess that's the only answer to your first question.
Question 2: no idea. Probably not what I'm into. I'd love it to be GungeGIrls or Bound2bMessy but who knows?
Question 3: we all discovered it for ourselves, on ourselves, probably when we were 6. Unless someone introduced you to it. This site started in the late nineties. Magazines like Splosh! have been around since the eighties. The pie in the face is cinema's oldest sight-gag. Who knows? Who cares?
Question 4: differs for each person. The least appealing thing for me is its language: "great coverage" etc
Question 5: this site
Question 6: don't know, don't particularly care
Question 7: don't know. Read $4K the other day but with a cheap camera, a few buckets full of custard and a well lit cleanable room you can do magic
Question 8: this question looks a little "I have this friend who..."

Just talk to them about it. Helps if they're kinky. People either like it or don't. You can't convert people to it, only turn them on to it
Hope this helps. The great thing about this is, someone will probably come along and say something completely contradictory...
And what's the drama?