What's the difference between solid and stranded cat5e-6, etc cable? What does each of them look like and what's the purpose of each? I've searched online but the information I've found is unclear. I guess one is used for patch cables and the other isn't...?
The difference is in the physical construction of the copper conductor itself. If you strip the end of the cable, separate the conductors and bend one you'll see. In a solid cored cable the core will stay bent and feel rigid. In a patch lead they are more floppy.
The non-conducting internal components you mentioned are there to maintain the electrical and physical characteristics of the cable along its length. These vary from manufacturer to manufacturer. Sometimes you'll also see a nylon thread or string, and there may also be talcum powder