I have another tip!
Michael Pollan has a dictum for health: eat "real food". And by "real food" he means food containing only ingredients your great-grandmother would recognize.
(Or someone else's great-grandmother in some other region/culture, if you're eating food from somewhere else. Food you'd see on a farm or in a market before the rise of industrial food processing, is the point.)
A way to do that in a modern supermarket is "shop the edges" - do most of your shopping in the produce section, the bakery, for non-vegans the meat and deli sections, the fresh unprocessed food sections that are located on the edges of the building in a typical American grocery. Then duck into the middle of the store for staples like rice and beans and oil and stay far away from the frozen food section.
And when you do that - when you avoid pre-processed food, buy fresh ingredients, and make your own food - it's easier to eat vegan because you control every ingredient that goes into your food. Your food will not have mysterious chemicals that may or may not be animal derived. Your food will just be food.
And not only will you be eating more ethically, you'll end up a lot healthier.
Green roofs do need more support. But think of it by percentages. A one-story house is going to need significantly more structural stability than normal to support a green roof. If your building is already built to support 10-20 stories, the additional weight of the green roof and the reinforcement underneath is not as big a concern.
Personally, I would prefer solar panels on roofs and green spaces on the ground where the public can enjoy their benefits. But more green is better than less.