1/ I can't say too much about the lead thing. What does the shader look like. There isn't duplicate faces in the same ares I presume. 2/ The pattern is a texture map I take it. I haven't hit this sort of case before really. Although I've noticed that using the UV editor in Carrara you may need to rotated the geometry before uv mapping the piece so that you know where the left edge or the texture map should end up. Booleans should make a lick of difference on uv mapping IMO.