[villagetinker]

OP, I do not do attics for many reasons, I tend to react to the blown in insulation, you need to be very careful where you step, and of course the heat, also, in our house all wiring penetrations from wall to attic were sealed, making it difficult to impossible to use an existing cable to pull in new ones. You might be much better off snaking to wire in along the soffit. Before you start anything look at the interior of your roof, there was a vintage of houses that had insulation with a metal (or metallic) surface that tends to interfere with RF (think cell phones and TV signals). Outside antennas are allowed WITHOUT ARC approval so you may be able to find a suitable location near you low voltage panel, and save a lot of work. Finally look into wireless for your internet, and eliminate the need for wiring entirely.
Hope this helps.