In question 1 I think it should be "are" instead of "is". Driving me nuts over here...
I was thinking about my answer when I ran across a problem. INTP-compatible groups tend to have INTPs in them! And then the question arises: is the group INTP-compatible because of the inherent nature of the group & the non-INTP members, or is it INTP-compatible because there are other INTPs in it?
From personal experience, within the US:
- Programming groups are highly INTP-compatible. Programmers are a bunch of NTs & STs, with a bias towards I, N & T. Programming is intrinsically a lonely, creative and rational endeavor.
- Board game groups. Not the endurance boards games (epically long board games that have less strategy-- like Axis & Allies), but shorter and tactic/strategy-intense board games. Settlers of Catan, Dominion, Ticket to Ride and the like. Also card games. I think Settlers of Catan is especially INTP-compatible because there is a strong people-skills and negotiation emphasis in the game, which forces INTPs to interact to get what they want.
- Art groups! I went to a gallery showing and had an enjoyable time talking to artists. I was there with a photographer who was displaying some of his art, and he's also a *NTP.
- Burning Man. Burning Man takes all types, but I think there's an emphasis towards Ns, with a general acceptance of all types. I felt very at home at Black Rock City, and I'm going back in a week!!! When I moved to Seattle, I made my first friends at a regional Burning Man event.
Outside of the US, things get trickier. I think you can look for societies that have a lot of intellectual activity and value those aspects. Or societies that have some recognition that some people want to be introverted & obsessive about intellectual pursuits. In some cultures, introverted & obsessive meant going into the priesthood or becoming a lawyer. In Japan, being an INTP would probably fit in very nicely to the culture.
I think in general there has to be an acceptance for people to be a little bit weird or off. I'm not sure if highly religious countries would be capable of handling that. Countries that value objectivity & abstractness would cultivate INTPs well.