One thing I've been hearing everywhere from hard surface artists is they really don't mind N-gons if the meshes's are non deformable, they are generally re-topo'd at a later point. Watching Tor frick, James Taylor, David Lesperance and more they all mention that if working with non deformable geometry, you generally just control the form with the basic premise being if it looks good then it's ok. As it takes a lot of time to work with hard surface objects and maintaining loops effectively you spend more time thinking than doing.
Characters on the other hand, require you to stay away from N-gons exclusively.
Yes, true - although some packages will flat out refuse a mesh if it isn't quadded. General rule of thumb and a good habit, especially getting hired into a junior position - if it isn't quads you haven't done it right.