I've always believed (and my mother drilled it into me, god bless her sweet soul) that you don't ask a) when they're having kids b) how much money does (s)he make, or even when they plan to "make it legit" (aka get married). There are a few others, but the answers to those questions is this: None Of Your Go***mned Business!! When I start a conversation with someone, it's either with a very neutral one-liner or a "Hi, I'm _____, how are you?" If it's someone I already know, I'll keep things very neutral and leave the personal stuff alone, and will only talk about those things if THEY initiate that conversation.
When someone asks me when my S.O. and I are going to move in together, I shoot back, "When we're ready, and not a minute sooner, capiche?", then I walk away. Shuts them up 99% of the time. Good manners have become an endangered species, it seems.