Stuff will vaporize from the herbs themselves, which will only dilute your spice vapor.  For the strongest hits, don't add herbs.  Another option is to pre-vape the herbs so they can still soak up the spice but will not produce much vapor when they are vaped again.

Regarding the torch flame, you don't want it to make the ceramic glow.  You want the dim blue flame a cm or so away, closer or farther away depending on how big your flame is.  The ceramic will be near glowing, especially when the flame hits it, but you don't want to get the whole thing glowing.  The hottest part of the flame is at the tip of the bright blue flame, you definitely don't want that bright flame tip touching the ceramic.  In bright light, the dim blue flame is barely visible.  This is basic functionality of the GVG, so practice on some plain herbs to get a better idea of how it works.  It sounds like you just need a little practice.

Happy Trips!