no
Pioneer species
Yes, Russia did not colonize any part of Africa.
No. Since Mexico became an independent nation in 1821, it hasn't tried to conquer or "colonize" other countries.
NONE
There are obviously a few in Mainland China, and a lot more in other Chinese areas like Taiwan and Singapore. Most animosity against Japanese by Chinese comes from Mainland China.
China did not colonize either. Colonization implies a movement of your population and control into what was previously territory that did not have your population or was not under your control. China established a system of vassalage, where any state near to China would come under its strong influence as a tributary state and would receive Chinese protection from "Barbarians" in return. Korea was a "good" vassal and remained in the Chinese sphere without problems from the 1300s until the late 1800s. Vietnam was a "bad" vassal and so they periodically revolted against the Chinese. Therefore Vietnam was a Chinese vassal intermittently (more off than on) ever since the year 1010 until the French colonization in the mid-1800s.
yes
Yes.
Yes they have.
Yes, some Chinese spoke German. I know some German speaking Chinese. Some people of Chinese ancestry undoubtedly live in German areas and have adopted the language. Certainly there are Chinese people who speak German because they work in international businesses. But German has never been the primary language in any area that is culturally Chinese.
Chinese students and graduates are interested in global affairs as they pertain to the rapid changes in Chinese society. They have interests like any other in specific areas of study as well as those that interest them. While Chinese culture and business methods and practises are different from those of other nations, they are dedicated and hard workers with the same goals as any person.
Any aircraft are from earth. There is no scientific evidence that aircraft from anywhere else have visited us.