Automatic bump mapping In the image, I know that setting Normal to a value (other than 0) in geometry will create a bump map from the texture onto the material. It works well and I'm doing this for the hair of a human model. What is the difference between positive and negative? Does one bump in one way and the other the exact opposite? (So if 1.0 bumps it outwards by a certain amount, -1.0 bumps it inwards by the same amount).

But my main question is the Bump Mapping Method and Space. What do these do exactly? I looked up on here and it doesn't specify their purposes, only shows the available options. What is the difference between these options? I found that Original method (which will for some reason disable Space) looks the best to me but I want to make sure that option is the most appropriate for the situation I am in.
As far as I see, if normal is positive light colours bump outwards and dark inwards, if negative - the other way round.

The rest doesn't seem easy, but here are some links. I think "Method" is mostly about quality:
http://kishalmi.servus.at/3D/bumpcode/

"Space" should tell in which space the normal vector will be stored. But the results look strange.

Anyway - why not use cycles?