try using morphs and transparency map settings on the skin. Your transparency map should be a texture map similar to your color map but in black and white, with pure white in the places you want the skin to appear and pure black in the places you want nothing. You have to play with the transparency fall off effects to get a good result. Also, you will need several skin textures, and render your image with each one and composite them in layers in photoshop. it will take a lot of playing around and messing with the settings. For your bimp maps, use a regualr bump map, but increase the brightness a good deal and then paint pure black on the areas where the holes will be to give it that deep look.