The wait very well have made a big difference in the end result, a week is a loooong time in shelf life of fish. Try to do one same day next time, I think you will have better results.
Had you frozen it, it would have more likely turned much more mushy, that’s just been my experience.
When you drop the fifteen lit coals, I generally drop them ON a piece of smoke wood so you’re sure to get some right away.
For trout, I don’t think I’d use much more than one or two fist size pieces, maybe more for salmon.