This version of Lex Luthor will be very intimidating. I'm sure he'll be the second most protected man on Earth behind the PotUS. He'll be young, either inheriting money or being a very young success case, such as Zuckerberg... Depends if they want to include some Lionel. Lex Luthor's role has been rumored to be a 5 picture deal.
He'll be the puppet master of the DC Universe.
I'd imagine he'll have very little screen time with Superman. I'd imagine most of his screen time will be with Lois (from the "good side"). The majority of his screentime will be of his impact on society and how he's contributed. He'll look like a good guy. The Savior of Metropolis. He may always feel like he's doing the right thing. He may always have the point of view that he's the man to save Earth, i.e. alien hater...
I'd imagine at first, Superman will try to protect Lex from Batman. I could see Superman and Batman squaring off at a LexCorp building in Metropolis. Later, Supes goes to Gotham to investigate Bruce and that's when you introduce Diana.
Bruce and Lois investigating Lex. Clark and Dianna investigating Bruce Wayne (Clark knows who he is, Diana looking for her property).
Maybe WW helps Superman with Metallo, Batman outs Lex as the mastermind...