I am curious who exactly are the main villians of each season, I know who are for the last 3 but not the others.

While I was watching during later seasons I didnt catch up on interviews from the showrunners but did we ever get an explanation of how come in season 5 finale-season 6 premiere they introduced zod, got rid of him only to bring a clone of him in I think season 9, did they just change their minds and say they wanted a whole season arc devoted to him?

I am curious has ever been lost media involved in this franchise, like a lost episode, a promotional video or photo or a lost script, something like that.

I noticed in this episode (S9E04 Echo) Jor-El refers to Clark by his human name, rather than his Kryptonian name. I think this might be the first time, but I'm not sure. Is this a trend that continues, or was it a mistake?

https://smallville.fandom.com/wiki/File:Hourglassvision.jpg

It would be set in the Arrowverse, but not cross over because it would not work by my opinion. It would show Tom Welling Superman in Metropolis saving people and working at the Planet and what not. Gotham should also do this and called it Gotham: Batman Begins