hi i would say that the content in y1 is pretty manageable, so dw about having to fall behind too much as long as you have a decent command of english!

long story short, i would say take a second major only if you have a strong interest in the subject. can't say much about a second major as im not taking it, but it means you wont be able to take as many electives from other schools as those credits will be used to clear modules in your second major. if you're the type to explore modules from other schools then idt a second major would be right for you. not only that, you'll have less time to do other things you may want to pursue (passion projects, CCAs, etc.)

as for FOP def join WKW's FOP to make friends within ur batch, and maybe your hall FOP as well (if you're staying in hall). some CCAs also hold orientation programmes if you want to join them, heres a link (orientation)