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.
The Blend method works in CS6 as well, but the gradients on strokes make it a bit easier in CS6.