That's exactly what these forums are for. Post up your stuff, and people will give you crits. The more people that see it the better. One person can give their own opinion, but the more opinions,...
You would just have to layer your blood over the rusty door texture in Photoshop. You're basically just updating the current texture to have more detail. If your blood texture has a white...
Your object is probably too small based on the default scale of the scene. Is there not a way to change the chamfer amount to be relative to world scale rather than object scale?