Some questions about warpriest training.

Does wearing the opposite kind (light for heavy, heavy for light) negate the bonuses you'd receive, does it actually penalize your char, or can you wear a mix of both and still receive some benefit from the light armor that you are wearing?

Do all gear slots count towards the warpriest bonuses?

Does all gear count either as light or heavy, or is there a "neither" category. If there is a "neither category", how does this affect the bonuses?

How do the following materials fall on the spectrum?: (heavy/light/neither)
-Wood
-Bone/ivory
-Gem
-Dragonscale
-Stone

Just trying to figure out how one would maximize the benefits. Thanks!