I had assigned to work in Korea before, and I have been returned to Korea several times. I can share my experience with you.
At time, while I was in Korea, most koreans speak Japanese. Only few speak English. Some koreans who learned Chinese (mandarin) and they speak fluently. About the girls, they are the most beautiful asian girls to me where make in comparison among those girls in Taiwan, Japan, and China. But, they are not the hottest.
Korean girls like business men and professionals. They like Japanese, European and Americans. Chinese is OK, or soso. If the korean girls is married to the foreigner, the government will encourange the girl to serve her husband, I mean to take care of him for life.
I hope this information may help. Good Luck