I personally know the team trying to build the first production electric plane. One of the team members is an ex-engineer from NASA who was fired after trying to resuscitate one of the former kan-jis. Kudos to them !
You can become extremely proficient in the language and be highly sensitive to the culture. You can also spend 10 years in the country to the point were you grasp practically everything, no matter how much randomness is involved in the conversation or the place and time it takes place.
It does not matter. Majority of foreigners, westerners or not, won't have real local friends in English speaking countries.
Even though you do acclimatize to the culture and language you might still not be fond of it. I lived in countries were it would have been easier than in others to interact with people, but in the end I wasn't able to because I either wasn't a fond drinker (commonplace in all english speaking countries) or I didn't enjoy being involved in mundane silly-office conversations during the smoke break.
Most of the fresh expats can't even realize what they are getting into when they move into another country. If you are deciding to do so and you come across this post, do it, go and check it out, but beware that your inner you will never completely mold to that place.