I translated all my certificates myself when applying for one of the schools in the US, and it turned out fine (I assume it is because I'm admitted ). you don't have to translate it word by word, as long as they know what the certificate is all about then it's going to be fine. just make sure you have someone to certify the translation for you (as in get it stamped). pegawai daerah, pengetua and etc will do.

yup. and well if you're like me, who's such a perfectionist, you'll try to find the logo/badge (like the one in the original certificate) on the internet. it's not that important, just that it'll look nicer. but having just text on the paper won't hurt your chances I guess. and the part where there's usually a signature of the principal/director/chairman or others, I just put their names, no need to copy their signature to the translation. (I wonder if there's anyone who actually does that, hehe)

just to be safe, try to ask anyone who has applied to NUS before about this matter as it might vary from school to school.