Yes. They will have some places for outsiders. So no worry
2) KCS is local stream and KCIS is international stream ( more english than Chinese and likewise ). Same applies to the primary school
3) they will only have one English subject. Others are all in Chinese. Can't really comment a lot here as there are a lot of mix 混血兒 in the class and their English is really good. Some Mainlanders English are really good as they put a lot of effort in this subject. As compared with some of the really local Chinese school then the level is good.
Yes. They are differences.
While KCS is in K3, KCIS will be in Grade 1. They will stay in the same campus for until Grade 2, then they will move to Bermer Hill.
If you thinking of other 直資 or 私校, I would say Yes. 參加比賽,有冇獎不重要,重要的是俾學校知道你有心培養小明友。 I have friends with no award (but have a portfolio to show the school how you will develop your kid) have been admitted by St Paul Co-ed
So portfolio is important for the school to understand you more. But I think the school will only look at your porfolio when you are selected for the 2nd interview.
Portfolio usually is to be submitted with the application form. Of course, if in any case if you have supplement info including nre certificate , you may then submitted during the first interview or 2nd interview.