ambient + diffuse (light is additive) the diffuse term calculates per light and doesnt factor in ambient light. so you add it. also your forgetting your reflections ((ambient + lambert) * diffuse map) + ((specular + reflection) * spec map) its can be handy to put in a diffuse and reflection power multiplier so that things…
The diffuse map is the image you've already done. It's the base color image. It has a bunch of other names, but diffuse is technically the most correct.
Started the texture for the Kobra: Currently it is 1024^2 normal, specular and gloss (no diffuse). The lens is a separate item with a 128^2 diffuse and alpha.