Honestly, if we accept this as a new beginning for Superman, then most of the things mentioned here are the last things I want to see in a sequel.
You want Lex Luthor back as a villain? Fine. Take him back to his roots. Enough with the businessman/secret villain stuff. He started out an arms dealer selling weapons to both sides of a conflict. Bring back A-hole Luthor, before he got a first name. Or, bring back mad scientist Lex Luthor. You want Cadmus? Make him the head of it, a chief researcher with twisted motives. Make Metallo its maiden project. (Or Power Girl. Kate Upton can play her.
) Just no more Gene Hackman Luthor or Superman animated Luthor. It's been done. It's been done well, but it's been done, whereas we haven't seen mad scientist Luthor since the Superfriends.