What a great read this as been, it gives me some hope and reassurance as a newbie who just made a bunch of rookie mistakes. I guess I'm not alone. I also learned some stuff that I didn't even know I needed to know, so that's always good too.
Good for you doing a fishless cycle! 2ppm ammonia is IME the best amount, too much & it can derail the bacteria, too little takes too long. (that was probably in this thread but, well, I didn't want to read it all again, lol. Maybe I should, as I recall it's good 1, no wonder it's a sticky.)
Yes, if you do the dilution math, larger WCs are more effective than more frequent small 1s in reducing pollution. Nitrate is the easiest way we can test but there are likely other "things" too.
You should start a new thread in newbie or general freshwater forum, we'd love to hear about your big new tank & can help if you need it...we all have opinions & like pics too.