For fishing cable through walls, my father in law (spent many years installing alarm systems) has taught me many tricks for fishing cables. For my front porch camera install we drilled a hole through the brick from the outside and sent a metal fish tape down through that hole to a small hole cut in the wall near the floor on the other side, inside the house. Once it got to that access hole inside, we used a coat hanger bent with a hook to grab it and pull it through the wall. Then taped (very, very well) the Ethernet cable to the fish tape and just pulled it back through. Fairly simple and worked pretty well. If you have Insulation in the wall or a horizontal fire stop, things could be significantly more involved. I'll try and remember to get pictures of it tonight. Running cables through walls can be a hard concept to grasp if you have no building or previous cable running experience. A scope is definitely a good investment, just to see what's inside the wall.
Also, use a metal or fiberglass fish tape... Anything else and if it snags up, you can't push/force it through. But be careful thou, we found the ONE wall in our house with insulation, and as I was forcing the metal tape down it bent over and got itself in a loop. Even though it should have just pushed itself through.