Its definitely not too early. IME coho are in there from sept to as late as december, but the 'peak', if you can call it that, is through most of October so coho should be throughout the system top to bottom nowadays. You probably are not doing anything wrong. Some days you limit out in an hour, other days they have lockjaw and you cant get a hit to save your life. I find they also come in waves so you get a bunch back to back then absolutely nothing for hours. Its the nature of chasing coho.
There was barely anyone near us and I don't know the area at all so that was probably a good indicator the water we were fishing wasn't holding any fish.
Maybe, but I would not assume that at all. The water changes all the time and what was good one day could be a devoid of life the next and vice versa. Once you get a feel for the type of flow which coho like, you'll find areas of action where there is really no one around you. Other spots seem to be consistently productive which is why you see guys camping out at 5 am to reserve their spot. It may take some leg-work but you will eventually be rewarded and have a nice little spot to add to your repertoire.