Well, I have asked shit loads of questions. He has his "wife" whom he refers to as his partner and then his girlfriend who is also his partner. We have done a load of flirting and he is up to speed on everything the same as I am. We've been through the "sex talk" and what is and is not allowed between myself and this other man. I keep my fiance in the loop as much as he wants to be- I bring up the subject to discuss it with him, as him how he feels about it, etc. If he were to have any objections then I would stop this.... emotional relationship as it's going on now with work guy.
Both of his partners are fine with me, they are very open with it and one even started calling me his "work girlfriend" before we even got to this point so that's no issue.
I'm doing my best to keep both feet on the ground, we are not sexually active as of yet, but cuddling is a big part of it thus far and I enjoy that immensely. He knows that my fiance is the only man I've ever had physical relationships with and all of that. He knows my history to a point and what I am and am not comfortable with doing.
Other than that, like I said, this is just new to me and I still worry about my fiance- but he seems to be on a "don't ask don't tell" kick. He knows it's happening, he's okay with it happening, but said that he's not going poly himself.