Level Design Portfolio Requirements?

I plan on becoming a level designer, but I am not sure what should be/ doesn’t need to be in my portfolio. I have several questions:1) Does anyone know what my portfolio needs/should be included?2) Is there a list of things that I must show?3) How far into the level design process do I need to showcase?4a) Do I need to create and show a level/game design document?4b) Do I need to show blockouts?4c) Do I need to show the post-blockout phase (actual art assets in the scene)4d) Do I need to show a playable level?4e) Do I need to show post-playtest changes?5a) For scripting AI or events: Should I just show screenshots of the code itself/ blueprints?5b) Is there a better way to show technical knowledge for level design?6a) Do I need to show that I know how to work with different engines? (Unity, Unreal Engine 4, Skyrim Creation Kit?)6b) How do I showcase this?6c) Do I need more than these 3? (Are there better options to showcase?)7) Does anyone know of any good examples of level design portfiolios that I should strive for? The only ones that I have seen are ones that have industry experience showcasing fully released games, so I don’t know what I can show without showcasing fully complete levels.Thank you. I really appreciate the help.