I sometimes see チャンコロ used on 5ch as a derogatory word for people in mainland China. However, I feel like シナ(支那) or シナ人(支那人) are more often used in my experience.
They are also called シナチク (or rarely written as 支那畜 in kanji). When you want to insult China as a communist country, you can say 中共 itself (probably short for 中国共産党).
I forget where I got this information from, but it seems like 毛唐人(けとうじん) had been used to insult foreigners(especially, Chinese/Dutch people) until the era where Japan opened its border and started trade with foreign countries other than Qing and the Netherlands. But then, it became a derogatory word for westerners rapidly because they look hairy and smelly.
トップバッター is not only an English word coined in Japan, but also a baseball term (I know baseball is a minor sport in Europe), so, it's no wonder that you don't understand what it means at all. The literal translation is "top batter" but it's actually referring to "leadoff hitter" in baseball (a batter who bats first in the lineup). Besides that, it means the person who is first in line to do something.