Why do you say that?
@Pat I have other important responsibilities than just this course, and I'm unwilling to deal with an (apparent) hypocrite who puts in the bare minimum amount of effort lecturing/developing problem sets but expects herculean levels of devotion because "their class is just that important".
I'd be more than happy to do supplemental exercises, but to put those supplemental exercises as a part of a tight deadline assignment and then randomly choosing what you're going to grade (thus artificially increasing my time commitment and decreasing your own in the process) is incredibly unfair and inconsiderate of my time.
I have 4 research projects, another course (which doesn't pull this nonsense) and a TA position where I'm the only experienced person - including the new professor - with the course material and expectations (so I'm training new TAs and Graders as well). Oh, and I also have a house/wife to help take care of. I'm so overloaded that I had to turn down the opportunity to get an adorable puppy that I've always wanted due to this semester's requirements, and this guy wants to make his course substantially harder than it needs to be? No thanks.
Would you want to deal with someone like that if you could avoid it?
@johnabs
Only grading some them randomly seems lazy and not conducive to learning (how do you know if/what you got wrong?)
Regarding the 57 hard questions, you said he won't grade them but you'll get 0 if you don't do them (I assume 0 for the course). So just "do" them. You don't have to worry about getting them right. Just make it look like you tried. You can get them all wrong and it won't matter. From the sound of it, I doubt if the prof will even look at them, they will just check off the assignment as being "done".
If you want to actually learn the material, you can always go back later and look them over and study them at your leisure.