The "Iron Liver" trait from Adventurers Armory differentiates between drugs and poisons leading us to believe that there is a difference.
This also means that poison use does not function with drugs and explains why the addiction mechanic is disease based. I think it would be better to assume that drugs are a mix of poison and disease rules, but that hybridization does not mean that you can apply any rules you want from either genre without further investigation.
I agree with this guy in that the DC's should account for high level play. Max ranks in a class skill at level 12 with a 20 in that ability is a +20 right off the bat, skill focus makes it +26, and if they have a class ability associated with it then fuhghet about it. I would rather reward that instead of "fixing" it. Gotcha DM'ing is how you know you're dealing with a child, but be mature enough to indulge their momentary delight even if your character dies, for there is another to take his place that's even worse than the last (Muah hah hah ha ha).
Glitterdust. Mind-blank is so situational that if it needs to be countered i have a feeling someone's trying to scry and fry.
Kid, I'd like to tell you a story about the player character that could. He didn't behave like a selfish prick when things went wrong, he didn't try to make the campaign about him, and he certainly used him being incorporeal to punch ghosts. With time and training he gained access to the plane shift spell and re-entered the material plane.