You have translucency fraction set to 1.0 Basically that means that you have 100% translucency and 0% diffuse. To fix this, set translucency fraction to 0.2-0.3 remove old map from translucency colour and plug it there diffuse map copy. Additionally you might want to lighten up traslucency colour map and give it a slight yellowish tint. You can do that with CoronaColorCorrection node.
As for normal map warnings, that is very easy to fix. Launch Corona converter, find and press "fix CoronaNormal gamma value" button, close converter and you're done! Generally you should never ignore Corona errors and warnings messages, unless you firmly know what you're doing.