it seems putting on screenings from dvds is okay now, the bigscreen is what truly seems to count (though i love prints, personally). went to a cig burns event at pcc the other week and both films were straight off dvd, to the point where - and youd think they would try and hide this at least) you actually say the dvd player commands (pause/stop etc) appear on the screen prior to it starting. did ruin it a bit for me but well its was cheaper than buying the dvds myself and one of the films was so good i didnt care. i think you would still have to pay for public exhibition etc though yeah, which might be a pain. though maybe theres a way of getting round it, not sure?
I ran a film club for years and it's kinda a moot area - if you have it as a members only (you buy a membership on the door which is the ticket, that kinda thing) then you get round 'public' exhibition. If you're running it in a place which isn't a pub then chances are no-one cares anyway and you can show what you want. Pubs I think have stricter rules about what they can and can't show and what they have to pay for. Obviously dpends on the landlord as well.
Weird areas I always found were permission - if it's a low budget film then you're kinda morally duty bound to try and find the director, and ask permission, but then it's sometimes not up to the director. If you're hiring prints of 'real' films instead of showing DVDs I doubt if you're ever going to break even, hiring prints and getting 35mm projectors and a projectionist...let alone trying to move a 35mm projector anywhere...they are huge beasts...
I think the Expoloding Cinema used to have a 'how to set up a film club' thing on their website, might wanna ask them or ask the LUX or look on their websites.
It'll be a labour of love any way you do it unless you show fucking Pulp Fiction 'outdoor' and 'secret' on some cunts roof and like having to deal with Time Out readers.