The answers to this one vary for the individual. When are you starting, when will you finish, how cold do you sleep? We had cold rain our second day out, and ran into snow in the San Gorgonios. We got snowed on in the Sierras and again two or three times in Washington. We used a 20 degree bag the whole way. We were fine in southern California, hot in northern Cal, and occasionally cold in Washington. We used a tent, so it was easy enough to sleep on top of the bag when it was hot without getting eaten by bugs.
I used running shoes in southern Cal., switched to boots in the snow - we were early season and had a lot of snow. People who were a week or two later, who didn’t have to kick steps in hard snow, were fine with running shoes. I prefer the warmth of leather for cold rivers and snow, plus the edges that make it easier to grip snow. But a lot of people don’t seem to think that matters. Train with running shoes so you can see how your feet handle them. My husband can’t hike more than a few miles in runners. We tried before the trail, and then again in northern California. He was miserable both times. We also had the problem of running shoes that started to fall apart within a week. Not happiness.
We only night hiked once and that was along the aqueduct where navigation wasn’t an issue. In places where there is sidehill, you won’t have to worry about getting lost. In flatter sections, you might get off trail. But generally it is pretty obvious - a brushy green tunnel. One concern I had is you can’t see the rattlesnakes that like to stretch out in the middle of the trail. You also can’t see the poison oak that sometimes lines the trail. Generally we would start the day very early, as day was dawning, hike until 11:30 or so, rest in the shade, such as it was, for a couple of hours, then take off about 2:00 or so and hike until 8:00 or so.
Ginny