Answer:

I've had friends who took STEM and they're fairly good at Math. I'm an ICT grad btw but I'll just share what I've observed. A few subjects to look out for would be Calculus (especially Pre-Cal, based on what they say), Gen Chem, Physics. But fear not, while being good at math is an advantage it isn't a requirement. I've had friends who didn't have math as their forte but they still graduated and was content with their decision. In my opinion, you should go where you think you can grow more.

In regards with the subject, I'm not sure if it depends on the school but my classmates had 8-9 subjects per sem. The same for every strand. They were packed during the first sem but was able to have a lighter schedule during the second.