I'm not sure how a post-grad is different from an MS or Ph.D student, but I'd say that the questions being discussed here have a lower bound at advanced undergraduate/beginning grad student, and extend all the way up into active researchers at all levels. Many of the "big-list" questions are at the lower end of this range.
While MO is definitely a strong influence on how we use the site, I think that we are likely to entertain certain kinds of broader questions, especially in the realm of applications. However, from a level point of view, we're probably similar.
I would hope that you wouldn't get scared away ! While the questions might seem out of reach, they do span a wide breadth of topics, on which few of us are experts, and so it's not surprising that many of the topics might appear inaccessible. There might be some crustiness towards ill-posed, unmotivated questions, but clear questions that aren't answerable by Google (see this thread on how to ask questions) will (hopefully) get a fair shake, even if they might seem basic.