Whilst I would agree with you that driving round and round a drive through is not a great idea as it contributes to pollution without any real kind of benefit to offset the harm, I can't agree with the rest of your messages about methods used by campaigners.
Having been on a fair few anti mcdonald's protests, I can vouch for the fact that as McSpotlight says, the litter returned to the company (and that used for street theatre litter suits) is stuff that has been picked up off the ground, dropped by McDonald's consumers, not stuff that the protestors have bought and eaten the contents. Maybe it's because protestors pick so much of the company's litter up that you think over-all only 25% of litter comes from McDonald's!
I don't think you should be too disparaging of the road sweeper. Obviously 70% of litter coming from McDonald's is not going to be true for the whole country, but there's a main street with a McDonald's near me where McDonald's litter makes up well over half of the litter on the street. So what the sweeper said may well be true for the patch that he has to clean.
As for getting our message across, we don't have ready access, or most of the time any access at all to radio and TV, so the only way we could verbally pass on the message is on an individual basis. It would take quite a while to tell someone all the info in a leaflet, and as a result every protest would probably only spread ideas to a few people.
Leafletting however enables us to reach a much wider audience, and for them to take away the information and think about it in their own time, when they're not rushing about on their way to work or shopping or whatever. All the leaflets I have ever handed out have been printed on recycled paper, so no trees got chopped down for them. But even if they hadn't been on recycled paper I think it is still justified to use paper for a positive end, as it will ultimately contribute to a change of ways of thinking and usage of resources, so that in the end the environment does benefit. Since the early 80's there has been a massive increase in awareness of the general public over issues such as deforestation and recycling, and this was basically brought about by campaigners banging on about these issues both by leafletting and other protests. If people don't know the harm they are contributing to then they're not going to change their actions and help towards a solution.