1 & 2: Maybe you could involve people from these communities / neighborhoods so you can know more about the local problems and be better accepted.
3: hard to prove the social side! Maybe if you have a fixed-ish schedule you can make a transparent calendar and tell people to come check when the smoothies / soups are being distributed in the schools. Maybe they would like to volunteer too. For the environmental side I think it's easier if consumers can see the products being made on the spot and understand the transformation process and where the veggies are coming from.
4: I actually think that's cool if the menu varies, but then you need to make sure the smoothies are constantly good;-) If you have regular clients you can also say something about what the smoothie will look like in the coming weeks
Revenue generation is pretty tricky in our case. Most grants we apply for give us feedback saying that our biggest problem is that we don't have a sustainable revenue stream. I don't want to go the corporate way because as you said this is a non profit.
As you and Anne-Laure Fayard suggested I'll try to add a donation button on our website soon. But what if donations are not enough?
The ad idea is just an idea, and I hope we never need to do that, but it's something we need to think about. Maybe we could limit the scope and the visibility of the ads. Or limit the type of company that can put ads there. I don't know exactly how this would work, any thoughts?