Extension of editor and custom GUI

Hi everyone, I've been watching the intro to editor scripting and I was wondering something. In the video they're creater the SoldierControllerEditor class that extends editor. From what I understood, it uses some reflectivity to be combined with SoldierController (which is not actually attached to theobject). Is that correct ? In that case, wouldn't that pose issues considring scripts in "Editor" folders aren't included in the release packages ? Or is the reflectivity doing the job and binds the actual scripts to the item ?

Also, is the PropertyDrawer the best way to go about customizing the GUI appearance of a MonoBehaviour script now ? In that case, is extending Editor useful anymore or is it pretty much a deprecated way of doing things, and only EditorWindow s are useful now?

Thanks in advance for your answers