I'm going to use vector drawable feature for action bar icons and notification icon, on my app.
With the announce of Android N, one of his most important feature is Screen Zoom (on Accessibility Improvements section). Another interesting feature is Multi-window support (see link if you want more info).
Does this means that we should use vector drawable also for launcher icon and other images used on app?
Vector drawable is not supported for launcher icons. You are, however, encouraged to use it everywhere else.