here is the answer on your first question.
however, I think if you don’t sprint, knee flexion movements are desirable. For instance, when you kick a ball in soccer, your hamstrings must prevent knee hyperextension. So they must be strong - trained at lower reps.
And by the way, knee flexion ex. are probably the only outright pull movements for the legs and ghr or natural ghr really builds powerful and big hamstrings.