How could I add gradients along an object/path (not following the path, but using it as a base, like inner glow) ?
For Illustrator CS6, simply apply a gradient to the stroke and choose the Across stroke option in the gradient panel.
For earlier versions of Illustrator a blend may work better.
Draw two paths.
Stroke one with the background color and one with the highlight color. (I used magenta so you can see the path.)
Select both paths.
Object > Blend > Make from the menu.
The Blend method works in CS6 as well, but the gradients on strokes make it a bit easier in CS6.