Blender Terrain texturing

Is there a way to some kind of overlay a terrain or selected part of a terrain with an image in Blender?
Right now, if I simply open an image as texture it'll stretch and size and whatever the image to fit the quad (sure, as they're on the UV map like this).

What I'd need is a way to tell Blender that it should lay the image above the selected faces in a way that they aren't getting stretched, scaled or anything, no matter what the face looks like.

 

Thanks, that worked very well
--- Post updated ---

Texturing the grass and road wasn't a big problem, texturing the kerbstone however was because there needs to be an exact was the image is laid over it (while it didn't matter for the other objects).
It didn't work by simply pressing any of the other stock unwrap modes and rotating the UV.
Is there some kind of "follow vertice line" thing?