Well, being a Korean, I infer it would be very hard to be objective, but anyway I'll try my best..
Guide Q1: Does their culture appear "friendly" on every non-korean national regardless of any country of their origin?
A: NO, it is not. Koreans usually don't appreciate foreigners, even from the time of our ancestors. Our culture was developed in a way that doesn't mix other country's culture with ours. So our culture will not look friendly for every non-korean nationals, since our culture only cares "Koreans" exclusively...
Guide Q2:How do they view foreigners, especially USA and other fellow Asian countries (Japan, China, and most of the south east asian countries)?
A: It depends on the country of their origin, and further the location of their country (e.g. Africa, America, South Asia, etc.) Korean culture has a kind of racial discrimination, which sees Americans and Europeans as superior people than the Koreans (generally), and sees fellow East Asian countries as our level, and lastly we see the rest, especially South East Asian countries as inferior than Koreans. They think Americans and Europeans as superior race. It can easily be shown by their attitude toward Americans and Europeans, where almost every young people would like to be friends with them. But some just treat them as same as the Koreans. Countries like Japan, China is closely studied by Koreans, in their history. They think Japan, China, Taiwan and similar countries are at the same level with Koreans. You can easily see that comparing how they treat Japanese, Chinese,with Americans, and Europeans. They are less friendly toward Japanese and Chinese. Sometimes, they hate these people due to some historical facts. Lastly, South east Asian countries like Philippines, Indonesia, Malaysia are considered inferior than Koreans. It can be seen in labor distribution, where people from SEA countries all work in factories, and only few South East Asians works in an office.
They are indifferent with SEA people, and they are mostly unfriendly toward SEA people.
Guide Q3: The most dominant feedback have been the word "arrogant" as a defining attribute on Koreans. Explain why you agree or disagree with this label.
A: In some aspect, the answer is YES. In some aspect, the answer is NO. As I explained above, Koreans' culture doesn't appreciate much about the culture of other countries. This is very comparative to Japanese culture where they accept the foreign knowledge and culture. It can be seen in Korean history, like 1592 Japanese invasion, and the principles in late 1800's. In 1592 Japanese invasion, known as (Im Jin Wae Ran) in vernacular language, Japanese uses the new weapon that time, which is a gun. Koreans that time had only few guns, and this couldn't be used widely in military. Another example, is the primary principles in late 1800's. A powerful governor of that time, (Heung Son Dae Won Gun 1820-1898) contributed much for the principle of refusing foreign cultures and knowledge in the name of protecting pure Korean race and culture. This was a kind of successful campaign, and for few decades foreign knowledge has never been transmitted to Koreans. These facts might be the reason why Koreans seem arrogant, because they don't appreciate much of foreign culture (from ancestors) and they don't really care about it.
In the other hand, Koreans are friendly toward foreigners as they get to know each other. Even though the situation varies when the "foreigners" mentioned above is from SEA countries, Koreans usually finds almost every foreigner good if the foreigners themselves are kind to them.
The general look on Koreans is "arrogant", "unhappy" and some other negative words. People at first sight looks very unkind, but they are usually friendly when foreigners contact with these people. The very example can be shown among Koreans at foreign countries.
I do hope this would be a good source to your report.