It’s important to remember that they need to come to observe how a family spends Shabbos, not so you or your guests can pry into their personal business. On that note, some cues that someone doesn’t want to talk about what you are asking them:
they give short answers
they keep telling you they don’t know when they obviously should know
they give you the SAME answer over and over again.
I once heard a girl telling another girl, “I’m just trying to understand this…” Do you need to understand this or are you being a yenta? Do you think this person enjoys you asking all these questions?
Do NOT tell other guests before the meal, “I’m having a convert or a conversion candidate over for the meal.” Even if the other person you are telling is a convert or a candidate, you are still telling their business to someone else and it’s lashon hara.
If you are the guest with this information, do not bring up the other person’s conversion at the table in front of other guests. It’s better to let the other person bring it up or even wait until you’ve clicked with that person.
It would be nice if people didn’t start talking as soon as they finish benstching and others are still bentsching. This is coming from someone who bentsches in less than 3 minutes. I’ve timed myself. Also, bentsching so loud that it’s distracting to those who are still bentsching is not cool.