This is just a free comment, not an "answer" to your question,
AND I am no expert.
I have already posted to your husband's question on one aspect of yours.
(If you didn't know he posted one, you can find it.)
I think that you and your female partner should agree to dress
conservatively, but well, your best business clothes appropriate to
the place you are meeting - shows respect. To some extent, the fact
that the investor will be bringing his wife will help, since you can
follow her body language, unless she is much younger. Whatever, you
don't want to upstage or outshine her.
Since he has chosen to bring her along and make the meeting seem more
of a social occasion, it may start with informal getting acquainted
and no business, but that will still be important, the impression they
get of you four. There is a chance that the only discussion of
business will remain general, just to get an impression of your
(plural) experience, competence, and compatibility with his way of
thinking, rather like an initial job interview that at best ends with
an agreement to meet again. That is what it is, isn't it?
And they probably have done this sort of thing before, can be
considered a team, he may value her judgement and impressions of two
Taboos? Talking about family, unless he raises the subject, but don't
ask him about his, unless he volunteers information. Let them lead
the conversation. (You really should try to learn as much as possible
about him and his business before the meeting.) If there is a
complete lull, have something to say about current events - but not
politics or religion. Of course, if you know about his hobbies or
community work, you could ask about that.
Compliments: about her apparel, his business, whatever.
Someone once wrote that a compliment only has value from someone who
really knows, i.e., someone who is an equally good performer at the
activity, has jewelry of the same quality, etc. Wealthy people know
what they have and what it is worth - and are accustomed to hear it
mentioned. Just say you like something, if you do, and don't gush.
And if you receive a compliment or hear an "I like that," just say
thank you and don't add any explanations, unless asked. (The remark
may not have been entirely sincere.)
In this kind of semi-social meeting, you all want to come across as
social equals, professionally competent.
I hope this is some help - and not off track.
Good luck! Myoarin