How to select outer edge of selected faces? For example, when faces like below are selected, is there any fast way to switch the selection from the faces to the edges that are marked as blue? (Deselect the faces, select only the outer edges.)
With the desired faces selected, go to Select > Select Loops > Select Boundary Loop.

If you use it frequently, right click on Select Boundary Loop, and add it to the Quick Favourites menu (Accessed by Q)