有關hku e&f

It is not a double major but a "combined degree". However, some companies just take it as a double major.
Once you are given an offer, you are considered taking E&F, and if you want to shift to BEcon or BFin, you should applied to the faculty.
Yes, a good Math. background will give people some advantages, but not much. The core Econ. courses, they only required simpliest algerba, and write the answers in words. For Fin. courses, normally what you should know is just how to read the accounting statement, and interpret it. Anyway, you need to take a compulsory Math. course in Year 1.
Some courses demand good math. background, say, mathematical finance, derivative securities, fixed income analysis, but as these courses are not compulsory, you can choose whether take it or not.
They have a formula to convert the CE and AL grades into scores, but sorry, I forgot it(Since it's already quite a time ago for me)
A final remind is that if you choose the business stream, no matter which university, things will worry you most should not be Maths, or whatever, but those Mainland students. Those monsters were born for exams., so normally the local students have less chance to get a good grade.

2007-02-22 21:08:25 補充：
For the admission grade, last year it's E&F slightly better. But I heard that UE is counted more heavily in UST(I'm not sure about this), so just ask your friends from UST for that.