The thing is, those questions demonstrate a certain type of playfulness in dealing with the subject. It is not uncommon for good students to think of this type of questions when they design their first tests, precisely because those are the kinds of questions that they like to think about themselves. What they fail to recognize is that those questions are incredibly hard for others precisely because of their playfulness.
So those questions are useful for quickly recognizing really good students (students that are so good that they transcend the requirements of the course and can deal with the subject on this playful level), but they should only make up a very small portion of any test. And teachers should probably warn their students about this type of question...
Also I write C++ for living and I was not entirely sure if "y = x++3;" was valid or not (turns out it is an error but "y = x+ +3;" is fine, which I would have guessed but would not have been quite certain).
Edit: Now that I think about, I believe that "x = (x++ == 3 + x % (x=x=3));" is undefined behavior. I guess the question is not asking about that but regardless, that's a stupid thing to ask.
Later in college, I remember hating the assembly tests where you had to keep track of what numbers were in what address, and whether you were adding what was on the stack or in some register or the address or what was in the address and making a mistake in the very beginning could ruin the whole problem. Not fun, not sure how useful, but certainly gave you an appreciation of what was going on.
Ask them about compiler errors. For example, what does "undefined reference to `vtable for Foo'" mean?
Then some style guide  might be helpful. Make them write the rvalue expression to the left of comparisons, because "if (3 = x)" is an error then. Or some "assert (this != NULL)" in methods.
Ask about semantics, like "What is the difference between a move and a copy constructor?" or "Write a program to demonstrate the difference between any two of static_cast,dynamic_cast,reinterpret_cast,const_cast,implicit cast" or "When should you use unique_ptr instead of shared_ptr?"
Actually, now I think of it... all the questions were related to operators, except the last one which was a trick question. If all the questions bar one were in regards to operators only, then this isn't a particularly good test.
It tests if a student is able to follow a program's logic with rigor. It tests if you don't interpret the code but actually read it "as is".
Question#1 and Question#2 are less intelligent.
Also, no template test? Are you testing C with classes or C++ ? ;)
I think that's the problem with a lot of first time test (or interview) makers, they make their questions into trick/puzzle questions where they want the test taker to guess what the writer had in their mind.
--edited because I skimmed over the last question and assumed it was printing the values of the variables not the strings--