A few questions from a sophomore in MYP

We recently received our course selection documents and I have a few questions:

Is it possible for me to take 4 HL classes and 2 HL classes instead of 3 SLs and 3 HLs? I’ve heard that this is an option at other IB schools, but our counselors only informed us about the traditional configuration. Is it something you have to ask about or can you just do it?

How difficult is HL (Further) Mathematics? I consider math to be one of the subjects which I am most proficient in, but my instructor this year (for AP Calculus AB) doesn’t really teach the material; he just lectures for a few minutes every class and makes us do bookwork. Normally I wouldn’t have a problem teaching myself the material as I have had many terrible teachers in the past, but I simply haven’t had the time nor motivation (he never grades anything aside from tests) to complete the classwork/homework which I am assigned. Because of this I usually end up getting high Bs to low As on calculus tests, although I’m pretty confident that I have the capacity to understand the material well since I’ve easily made As in every other math course I have taken. I plan to take AP Calculus BC and AP Statistics during junior year and HL Mathematics and HL Further Mathematics during senior year.

What exactly does the TOK course assess?