Its up to the grower to find out what he likes. Cbn might be undesireable to you, but some people do in fact like the feeling cbn gives. Also some trichs will amber prematurely, you really shouldnt chop at the first sign of amber.
Good info, but it needs a few corrections. CBD is naturally occuring in cannabis resin, which means thc doesn't degrade to CBD. In fact both share a common precursor(cbg). This means that the plant can't have a high amout of cbd and a high amount thc. When you talk about degregation you mean...
Silicon is a trace element used by marijuana. I'm not sure what the benefits are of adding it with your feedings, as i'm pretty sure tap water has enough silicon(considering the plants will barely need any).
Some nutrients probably would have helped this grow a lot. Also outtake is more importantant than intake, you should have two blowing out an one blowing in.