You might be interested in threads from the FAQ sections on "Sakoku aka Edo Period Japanese 'Isolation'", "Sakoku and Dutch trade", and "Commodore Matthew Perry and the opening of Japan":

In "Sakoku and Edo Period General Information" and "Sakoku and Dutch trade"

• How was the VOC able to get a trade relationship with Japan where other trading nations and companies didn't get access to Japan in trading? - 4 comments, over 2 years old.

• The commenters in this thread summarize the Japanese perspective on the situation and why the country's rulers enacted such tight restrictions on foreign influence, particularly Christianity.

• Why was the Dutch republic still allowed to trade with Japan during Sakoku, even though no foreigner was allowed to enter the country? - 1 comment, over 4 months old.

• The lone comment gives a summary of the situation as a competition between various trading powers which the Dutch won that had all other powers expelled.

• Why did the Tokugawa persecute the Christian population in Japan? - 16 comments, over 2 years old.

• The commenters here explore and debate the multifaceted nature of Japan's "isolation" during the Edo Period.

• Was the Edo period a beneficial or a detrimental time for Japan? - 8 comments, over 2 years old.

• This thread goes into how careful control over foreign influence in Japan affected stability and order in the Edo Period.

In "Commodore Matthew Perry and the opening of Japan"

• 160 years ago if you asked someone in either the US government or military how it could be ethical to force Japan to open up to western trade when they'd made it clear they wanted to be left alone, what would they have most likely said? - 11 comments, over 1 year old.

• The topmost top comment discusses general American attitudes at the time, while a top level comment below it goes into detail on the specific political and economic goals of the mission using free, internet accessible primary and secondary sources.

• Why did the United States want to open trade with Japan when they knew Japan didn't have many natural resources? (19th century). - 20 comments, over 1 year old.

• The commenters talk about events in China and the nature of 19th century Imperialism to show the value of Japan in terms of US interests.

Briefly on your first question: we used to think Tokugawa Japan was "isolated" but now we know that to be false partly derived from Eurocentric views of history. Indeed the very term for "closed door country" (sakoku) it turns out was invented only in the 19th century by Europeans.