Howzat,
If you were in Australia when you posted your first post, it would seem to me, that you were Mechalel Shabbos R”L.
Uniform is officially not Tznius? Not true. Individuals definitely play around with their uniforms, but I don’t believe that the official length is above the knee.
The episode you describe with 12th grade boys and girls – I have never heard of it, could be it’s true. I’m not here to attempt to defend it.
I too, have been to Melbourne and know the community extremely well (better than you, Howzat) and I also know Crown Heights very well, I have lived there, not just visited. And no, there’s not much to compare at all.