Just a very simple question, I have read around the web site and it seems that I can create a working game including all characters from scratch, is that so?
Sorry if the answers are there somewhere I must have missed them if it is.
Yes, you can. Just needs a lot hard work! Characters and textures you have to create outside Unity with, for example Blender and GIMP (they are free.) Mostly everything else is covered in Unity.
Start learning with some tutorials, and when you feel like you handle things, start making a game from scratch! 
That is what I was thinking, your characters are made outside the framework of unity.
What is the common unit linking size to all packages, eg how tall to you make your character compared to the landscape within Unity?