I think there are a few things worth adding to this. The first thing is that the notion that someone might have many words for, e.g., snow, and thus be able to discern more qualities of that thing is just nonsense. This way of thinking is putting the cart before the horse. Obviously, the more you know about something, the finer distinctions you can make in that thing. If making those distinctions and being able to talk about them is important to you, then you make a label for them, and you and your cohorts have a jargon. It happens all the time but really isn`t anything to get excited about, and it does not mean that other folks who speak your native tongue couldn`t, if they wished, learn the distinctions and the jargon that goes along with them. In other words, if we all cared about techno, we could all learn the labels. But we don`t because we have better things to do.

What this means, at least to me and others of my ilk, is that any language can expand to include whatever vocabulary its speakers deem useful. If you wish to formulate this into a handy rule, it would be something like the opposite of the Sapir-Whorf hypothesis: culture determines language. This explains why subcultures like techno geeks, surfer geeks, and computer geeks have such a quantity of jargon that to the rest of us is mainly meaningless. I would wager that no one would be so foolish as to say that computer geeks became what they are BECAUSE they learned the jargon. This also goes some distance toward explaining why, say, the Chinese and Gaelic speakers can have no words for yes and no but can still manage to express the concepts, and why the Japanese have a word that essentially translates to 'no', yet they rarely use it. If they need it, it is there, but culturally it isn`t all that useful.

As far as the relative difficulty of learning (insofar as they are separable) the grammar of a language and "how to think in that language", or what we might call the pragmatics of the language, anyone who has seriously tried to live and communicate in a culture (and language) really different from her own, knows that these are related and equally difficult pursuits. It is one thing to learn French at home in England and never use it except maybe on your sightseeing excursions to the Eiffel Tower. You will probably not notice that you do not in fact "think" French thoughts. It is another thing to, say, go to live in a new culture and see how far your perfect grammar gets you. There will be many times when your well-constructed sentences elicit blank stares, uncomfortable silences, and even worse (incidentally, I know from experience; I am an ugly American living in rural Japan). Until you know the pragmatics, you can`t use the language like a native speaker. You have to learn the culture that drives the language before you can really be said to speak the language with anything resembling fluency.

Or, as I think Chomsky said, every language is capable of generating an infinite number of sentences. But in practice the sentences actually used depend on a lot of factors, one of which is the pragmatics, or cultural constraints.

And one last thing...the guys who did the color terms in language studies were Paul Kay and Brent Berlin and the studies are referred to as the Berlin-Kay studies and the chart as the Berlin-Kay Color Chart.