Basically, you may be required to obtain a working permit (visa) to work in Hong Kong / Macau legally if you are a resident in Chinese Mainland. But in Chinese Mainland, there seems no specified requirements for the working permit, i.e. you should answer "Yes" when you are pursuing career in Mainland if you are a Chinese resident.
As per the conversation with the HR manager in the recuitment talk today, 1000 characters (around 130 - 150 words) limitation aims to assess the candidates' presentation, demonstration and summary skills. So bear in mind that the system delete the excess characters and HR may not fully understand what you said.
"Your answer should not be more than 1000 Character space (include letters, space and punctuation)."
这个要求。。貌似得用文言文表达才能满足规定字数,150字的英文已经超1000 character了。