This is where I currently stand, with this UV grid(?). The texture this model came with (I could never make a model this good looking) is nothing but a grid of different colors. A little less clear on the image there are some grey lines, indicating different surfaces on the model. How could I extract only those lines into an empty PDF, or anything similar, so that I can texture it in Photoshop? Thanks for any help.
Those grey lines are the uv shells for the model. Which means it’s already been unwrapped. That grid texture is nothing more than a “helper” texture. It’s used to find areas in your unwrap that are distorted/stretched.
Did the model come with any other textures?
If you want the uv mesh as an editable image just go to the “UVs” menu on the bottom of the window. Select “Export UV layout” and select your options for the export/filename etc.
I am not entirely sure, but you probably have to select everything in edit mode first, before you export your UV layout the way Macser already described.