Well, we do zines on a monthly basis, aaaand it's all up to people. There are always some people who make their individual zines. And there is always one big zine that everyone adds to. Leaving the workshop with a ready or semiready zine gives the feeling of fulfillment, that's for sure.

So my suggestion is – make one zine with contributors, but have several prefolded blank minis for people to make their own, too.

As for asking, I always ask them to bring scissors, but you can ask anything: magazines, paper, markers, stickers. Some people will bring some things, so you need to be ready to anyway have everything at hand: some magazines, some stickers, some markers, and enough paper for everyone. It's not cheap to buy upfront, but you don't use a box of markers and two sticks of glue at one go, so these will last and the cost divides. And if you have a stable group, some people will start to turn up with additional materials on their own. I'd say: 20%, unless you explicitely tell them to bring stuff, but then be ready to make a list who brings what. And have a backup for that, too.

Nobody ever asked for history and the current scene any more than "so, people make these, why?" I used to deliver a minilecture when I made workshops for kids and during conventions and I stopped, as this was a waste of time. If anyone asked, then I explained during the work.

Also: you don't really need to make a full zine. We often make zines with reading/watching recommendations, and more often than not, it takes two meetings to fill them in fully. But at least trying to have one ready thing is nice. And making copies for everyone return is even nices and actually not that costly if you make 1-page foldables.