Your Legal Rights - Law concerning commercial property.

First of all I’m sorry if I don't seem altogether here, I’m not the brightest little cookie. I have a question for all the law buffs and budding lawyers out there concerning the consumption of Ecstacy on commercial premises.
Here's the scenario:
After last night I was chatting to a DJ and he mentioned as this place is so boring he wished he could find a hall to hire on Thursday / Friday nights so he could set up his equipment and get friends round to dance the night away. I mentioned that I own a shop and he was free to come round and play any day he wanted inviting all his friends. After getting home I realised that this may have legal ramifications concerning Drug and Alcohol consumption that inevitably goes with this kind of event.
Here are some facts for the Question:
The premises is not licensed for alcohol
I don't plan on selling any alcohol
I don't plan on selling or encouraging any drugs
I don't plan on letting in any under age people
These events will only take place after hours and will not be open to general public.
The shop also has a house attached to it (So I’m not sure if it would be classed as Residential / Light Commercial).
It is in a built up residential neighbourhood.
My questions follow:
Can people legally drink?
What happens if the cops come and shut the party down and find Ecstacy on someone (Do I get in trouble or them)?
What happens if someone OD's (Do I get in trouble)?
I did do research on this for about 3 hours this morning but I couldn't find anything useful except law documents containing words of more than 3 syllables (Had to spell check that one) which I can't understand on a good day!
It sounded like such a good idea last night but I don't really want to go to jail / lose my shop because someone gets busted.
Any help would be appreciated!!!
Even links to 'dumbed down' law!
Cheers!

The following are all assumptions as I have no legal background or expertise:
I would assume that because it's a privatly owned property which will be used for a private party it would be the same as any house party. You wouldn't need a liquor licence unless you were actually selling alcohol - so BYO should be fine...
As for the drugs, well, just don't make it blatent - how were you to know people were going to do those nasty things? It's a private party, you can't be expected to do strip searches at the door...
If you don't want the cops to show up, then just keep the volume down to a reasonable level - that's probably the only reason why they'd be there at all... I doubt they'd shut the party down unless after they left you cranked the music up again - so just be sensible and keep your cool if there are police around...
If someone OD's, I would assume that there's be liability issues there - if someone trips over in your backyard and breaks their arm then technically you'd be responsible I think - but this one's better left to the legal people...
Lastly, there's the Legal Q & A forum on bluelight which might help - although you'll get a more Australian focus in this forum. So if this thread doesn't get too many responses or something I'll move it to legal...

I'd be more concerned about people ditching their gear if the cops arrive, because they won't be finding drugs on a person then, they'll be finding it on you property. This has always been a concern of mine.

After discussion with a friend of mines boyfriend (A cop) I found out that as long as I am not aware of anyone taking drugs on the premises then I can't be held responsible and they get into trouble. As for them dumping thier shit on the ground then it's up to the cops to prove that it's my shit just as it's up to the cops to prove that any night club owns the drugs found on the ground during raids.

Moving to Legal Q&A.