To answer the first question, I'm going to recycle my post from a while back:

For me it's a form of escape: in everyday life I'm career-driven, not overly friendly, hard worker, I set very high standards for myself and the people around me. Being a cuckold is a way to reverse the polarity, to take a break from my usual self: knowing that I'm being temporarily set aside for another, better looking, better equipped man, knowing that my sweet pretty wife is thinking of him and only of him, knowing that she wants to feel him in her every hole, the feeling of being... second, not first. It's not just the most arousing feeling in the world, it actually fills me with a sense of peace, it makes me feel happy, it literally puts a smile on my face.

A major part of my enjoyment also comes from letting other people know I have a promiscuous wife: it's not information I wish to be made public, obviously, I wouldn't want any of my colleagues, guy friends or relatives to know, but I do have an old female friend with whom I share almost everything, and I love knowing that she knows, I love that I can be openly "beta" (as much as I dislike that terminology) with her, and that she's cool with it. I wouldn't mind the neighbours to know, or to suspect, and of course it's fun trying to picture the lucky guy sharing all the lurid details with his buddies (provided none of them are in our same circle of acquaintances). Sharing it with people online is also fun.

As for the second question: in many ways I think that would be an ideal arrangement, as the other couple would obviously share the same need for discretion and safety. As an added bonus, it would be very exciting to know that another guy is getting to live his typically male FMF fantasy with my wife. So, yeah, I would love it if she played with another couple.