While PHP has low barrier to entry and there are a lot of people who tinker with it, PHP still powers a lot of production websites, far and beyond the hello world apps or the 'pictures of my dog' wordpress blogs. Your implication that there aren't "powerful stuff" websites running on PHP is just simply not true.
I highly suggest that in this day and age, you teach using simplified characters. For entire swaths (not to mention the overwhelming majority) of Chinese people out there, simplified is the way to go.
As I went through college (and I think everyone more or less goes through this) I learned to care less about marks as a whole and more about what I learned in that class/if there the knowledge is easily obtainable elsewhere. However, I'm fortunate enough to be in a field that doesn't explicitly require grad school (compared to say, those aspiring to be doctors) and that internship experience/generally more concrete interviews generally lessen the requirement for having really high marks.