Hi James,
In answer to your questions...
1) Just organise a great night, you dont need to worry about licenses in that situation. This is the only real way at this stage that you will have the number of people you are talking about also.
2) Not going to happen in a proper club. A logistical nightmare if they always hold stock. If you found someone who would let you do this, you or someone you employ to run the bar would need a personal license.
3) and 4) A little story to help explain what may be involved...
A couple of years ago i accidentally (long story!) ended up running, with a few friends, a large warehouse space in east london with some friends. Generally, we would take the bar, and you (the promoter) would take the door. I'm being simplistic here, and security costs and other bits and pieces need to be negotiated as to which pot they would come from, also if the promoter had clout he might be able to negotiatate some of the bar.
The cloakroom can also be an extra little earner if you run it.
Sometimes a promoter would want to run the bar. This was known as a dry hire. This generally happened if the promoter knew that their night was going to be a success (ie established). The promoter would essentially buy us out of the bar for a fee. (part deposit, part paid towards the end of the night). The benefit of this situation would be that we would get a nice fee for simply hiring the space out (with our security guys to look after it), and not needing to worry about stock / bar staff / cloakroom staff, and they would potentially get more money at the end of the night if the bar sold well. We would generally stay to keep an eye on the party anyway.
Generally, we preferred to take the bar, and not do dry hires, as we then could make sure that the people running the bar knew the venue, and secondly give employment to people we knew and liked. But if a successful promoter would walk unless we gave them a dry hire, we would take the money!
We only got the space for an affordable rent because the landlord was in the process of selling up, after it being in their family for thirty years.
It became quite an adventure, and we had to learn quickly! Because our space was very unique, an old leather factory, with loads of interesting rooms, and in a fantastic location, word got around and we had lots of independent promoters coming to us to put on nights.
The space was roughly 14000 sq ft, and didn't have any licenses at first.
To get that location into a place where we could put on fully open to the public, took a lot of work with the local council and fire brigade in order to show that we had a plan for every possible situation that may arise, fire escapes set out, medical stuff etc etc etc etc
Once we had done this, we employed someone with a personal license (to run the night, carry out risk assessments) to apply for a TEN (Temporary Event Notice, google them)
You can have 12 a year in a single building. 500 people maximum. At that time (2010 / 2011) you could put your whole weekend of events (different promoters) on one TEN.
I understand now that some councils are tightening up, and allowing only one night per TEN, which financially would have made it very difficult.
We had the space for 18 months before it was sold and largely knocked down to make way for student accomodation. On balance, it was worth it, a lot of fun was had, but it was also extremely difficult at times, and you wouldn't believe what type of shady and wiley characters can emerge if you look like you are making a success of it.
If you go down this route, make good friends with your security team, who should be well mannered and trustworthy, and should treat punters like guests in their house. Good security make such a difference! They should also be 7 feet tall and if needed, able to pull a face that could send a pack of snarling rottweilers running away when he (probably a he!) looks at someone that wants to cause trouble.
I hope this has been useful, just touched on it really, but i think thats enough for now. We generally had 500 people, which was enough to worry about to be honest. Remember the safety of these people are your responsibility, and if you mess up the consequences can be serious.
Start smaller, you couldnt put an event for 1500 people under a TEN license anyway, and work with someone who knows what they are doing to get experience and learn.
Best,
Matt