Also, re: IB, I did Math HL, and you can place out of a few courses. Because IB Math covers various topics rather than solely calculus, you might place into a lower course than a student who'd done well in Calc BC, but, since you've also done Further Math, you should be set to go into pretty advanced calc (and otherwise) courses.
I've yet to take a math class, but...
P.S. Here's a helpful site:
Brown Math Department Calculus Placement FAQ