Yes, yes and yes. Thoses are all central plotlines, amigo. Without the prostitution there's no free tuition plot. No free tuition plot ? Maya wouldn't have tried to join the HOTs and wouldn't have anything to do in the first two seasons. Josy wouldn't have any reason to join the HOTs to help Maya with her tasks either. Nothing would have happened with Burke and Mona. Burke wouldn't have no reasons to not help Maya in EP9.
Without the drugs plot, Riona, Lily & Vinny have no role in the story. The HOTs being present at the prep party and the trashing of the DIKs mansion don't happen. The plot of rebuilding the DIK mansion doesn't happen. The cliffhanger of the last episode doesn't happen.
Once again. You haven't really paid attention, I see.