Do you construct the shadow volume front cap with the faces of the mesh pointing towards or away from the light? (I assume the ones facing away from the light form the volume cap) Also, will the silhouette always be a closed shape? i.e. will the silhouette always form a closed polygon even if some parts of the mesh overlap one another from the light's perspective? If so, why? e.g. Why wouldn't the arm's silhouette on a human mesh form a gap at the armpit?

Bump. I really need some answers on this one, soon enough I'll be implementing this stuff for real, I'd rather understand it properly.

the caps [both ends... depends on the shadow method you chose] should point the same way as the volumes... if the faces on the volumes point out so should the caps

it will always be a closed mesh, but that doesn't mean it will not intersect itself

Ok, I think I understand, thanks.