"De" can be used to create a relationship of mode/way of doing something, e.g.: "ele está deitado de costas" (he's lying on his back).
The expressions "de modo", "de maneira", "de forma", meaning "in a way", always use de.
And both "de um modo" and "de modo" is correct.
How can we tell the difference between 'everyone' and 'every' when translation 'todos'. In this sentence it obviously means 'everyone', although the hints here and google translate only indicate 'all' and 'every'. I also seem to remember 'everyone' being 'todos o mundo'.