I have a FWB who's interested in exploring WAM. (We've previously done ws play). He's curious, but I don't think knows enough about it to have specific preferences yet.

What are some good questions I should ask him/things I should show him, etc? He's very open and kinky, and I want his first experience to be fun for him.

Start with a common interest perhaps unrelated and spark from there?

"Did you ever watch those old 90s Nickelodeon shows like Double Dare and What Would You Do? Where the people got pied and slimed? Ever wish you were on one? I have and I think it sparked something in me..."

Show some PG (or more) related pics and see what he says.

From there say "There's tons of stuff people use. I'd love to try..."

I brought up how 80's mud wrestling was in vogue, and used that to explain my love of gunge.

I suggest showing your partner some scenes that you find hot, it'll give him an idea of what you want to do.
(This was something I didn't do with my partner, she then did her own research and found a bunch of stuff I'm very not into).

You'll want to ask if there's anything that's "no way no how" such as does your partner hate a certain foodstuff, or suffer any allergies?