I want to run CAT6 wire through my house, from the wired west wall to the east end of the house, and I would like to do so as cheaply as possible. I do have an inside storage space under the living room, but I have failed at fishing wire through this space.
I now wonder if I can get away with attic installation. We have fiberglass insulation in that space, so I am wondering if I should run the cable through piping. Can anyone recommend the size of piping I should use? Would I be better off using copper tubing than PVC (PVC is so much cheaper).
Use Cat5e (good for 1GbE) unless you have a spectacular reason to use Cat6a (10GbE)*. Cat6 is essentially a deprecated spec, nobody should be using it for new installations.
They make structured cabling conduit. It's cheaper than the PVC electrical conduit. PVC works great if you need something rigid. Copper would be incredibly expensive and complete overkill.
Your local hardware store probably has a book on retrofit electrical and structured wiring. It would be a good buy/read for someone who hasn't done wiring before.
Consider using your air ducts to run the wires. It's really not a good idea as you wont be able to clean the ducts anymore, but people do it when in a bind.
*Consumer computers probably wont come with 10GbE NICs for another decade. There's very little demand and the technology is incredibly expensive (compared to 1GbE). Most Internet connections are still <10Mb anyway, so 1GbE is already 100x faster than the primary use case.