Game Design - Docs, docs and docs...

So I've been scouring over every bit of information to find the best ways to document a game idea, from the early drafts to the final versions. From what I've learned so far (Kindly be warned that I have just scratched the surface here. The more I learn, I'll keep updating this post) a game documenation comes from 5 separate areas of expertise - Writing, Art, Design, Technical and Marketing. Barring my limited knowledge in coding, I'm not much upto the task of Technical documentations right now. And I have no shame in admitting that I know jack about Marketing.
So for the time being I'll concentrate on stuff that I CAN cover, which all would be next in my to-do-list.

Writing	Art	Design
·         Story ·         Script	·         Art Bible ·         Storyboard & Mockups	·         Proposal ·         Concept Doc ·         Flow charts ·         Design Doc (GDD)

• Story           - Game Narrative, Backstory and context of the game
• Script          - Cut scenes, Dialogues

• Art Bible      - Look and feel of the game
• Storyboard  -

• Proposal      - Unless you have bucket-loads of money, you need to learn how to  pitch your ideas, to those who have $
• Concept Doc- Goes along with proposal. A very rough draft of the game idea
• Flow Charts - Tracking the flow of levels, worlds, menus

                           -Players decision making process
                           -Character arc/ Character development

• Design Doc - The leviathan of all the game documents.......

Game Design Doc (GDD)
This one mainly covers the Functional Specifications, Gameplay, Game Mechanics, Worlds/Levels. After referring to a lot of GDD's I think I'll present it in the following format :

• Table of Contents  - Its good to start with an appendix of the contents in the GDD
• Intro/Overview      - Understanding the game, General Info(Console, Genre, Demographic)
• Story Overview     - Just a brief idea about the story in which the game is set
• AI                        - How world reacts - Independently or to Player's actions
• Game Elements     - Characters, Items, Objects/Mechanisms
• Game Progression - Break down of Level/ Stage Design, How difficulty increases
• GUI and HUD       - Main Menu, Interactive interfaces (Mouse clicks, keys, tap/swipes etc.)
• Game Mechanics   - Levitathan inside the leviathan...............

Game Mechanics

• What/How the gameplay really is
• Camera, Controls, Characters
• Avatar(s) components and capabilities
• How Player controls Avatar/ Physical commands for player movements / Avatar's movement model
• How game control shifts over different levels/stages/worlds
• Non Playable Character(NPC)s

Now, I have noted down some other stuff, which I'm still figuring out where to fit best:

• Hitpoints
• Replayability
• Multiplayer