How much of the actual 60ftx40ft floor space will you actually use? Will that space be completely (more or less) filled with people, or will a smaller area be set aside for film viewing.
Also, have you consider the public ramification of public showing of films? Royalties, copyrights, and all that.
One problem you will have with a large crowd is the placement of the speakers. You will notice that most movie theaters have the screen and the front and center speakers up on the stage above the seated crowd.
If the speakers are down on the floor where the people are seated, it is going to be massively loud for the people in front, and hard to hear for the people in the middle of the crowd. In a sense, all the people around you are going to be blocking the sound for the people in the middle.
PA speakers can be placed on large stands to raise them up. PA speakers, while not the best is reproduction of sound, are rugged and made to be moved around. You don't mind too much of you scratch a speaker loading it into and out of a van. However if you have fine wood stereo speakers, you aren't going to feel too good about scratching them.
100 people equals 10 rows of 10 people; what kind of chairs will they be in? Common folding chairs? I'm asking to get a sense of how much space the people will take up relative to how big the room is.
If you can get the side and rear speakers up and back a ways from the people, the sound will blend that much better.
The front and center are going to have to be high enough to be heard in the middle and at the back of the room.
Here is an example of some MACKIE PA speaker and a link to some stands that were recommended for them -
The Speakers -
Mackie SRM450 v2 BLUE Bundle (Inc. FREE STANDS - EXCLUSIVE DEAL)
The Stands -
Kinsman Speaker Stands and FREE Carry Bag
Here are some other speakers shown on stands -
Yamaha STAGEPAS 300 + Stands
HK Audio Lucas Max PA system
I'm not recommending these, I just want to give you an idea of the type of PA equipment we are talking about. Speakers like this are available from a variety of manufactures at a variety of prices from amazingly cheap to outrageously expensive.
I would suggest a pair of 12" to 15" speakers for the front. Perhaps a single 10" to 12" for the center of a style similar to that show in the links above. 8" to 10" for the side speakers, and similar for the rear surrounds.
For subwoofers, I'm not sure, I really haven't checked out PA subwoofers. But for 100 people, I would expect a pair of 12" to 15" subs.
Placing and aiming the subs is something of a problem, and I'll have to think on that. Again, it gets down to how much of the hall space the people will take up and how much room there is between the speakers and the crowd.
In AV amp, I would suggest a good amp in roughly the £1000 to £2000 range, though I can't think of any specific models at the moment.
What I'm suggesting is a standard high-power high-quality AV amp with passive speakers. An alternative might be a AV pre-amp with active PA speakers. Meaning, an expensive AV pre-amp, but speakers that each have their own amplifiers built into them. The Dolphin Music site linked to above has both types. The problem is AV pre-amps cost a king's ransom. I would expect about £2000 to easily £3000, but it might be a possible option.
For a screen, I'm at a loss for a 12 foot diagonal portable screen. I'm sure someone makes one, I'm just not sure who.
Does anyone else have any other suggestions???