If I speak Chinese or Japanese, does it make it easier to learn Korean?
Mostly, no. There are a lot more differences between Chinese, Japanese, and Korean than similarities between the three languages. A Japanese speaker, for example, won't be able to communicate with a Korean speaker unless one speaks the other's language. It does help you to memorize some words though. Many words in Korean, and Japanese, are based on Chinese words. It is true that a Japanese speaker will find it easier to learn Korean than a French speaker.