Working on the Justice League movie right now. I'll post some info. Feel free to ask any questions and I'll try to answer what I can.
Darkseid is the JL villain, obviously. The first movie ends with him being teleported elsewhere and the League realizing they need to recruit even more (see more about that later) to stop him when he returns.
Superman is absent until the very end. He comes back and delays Darkseid just enough so they can send him somewhere else.
Batman and Superman have some nice back and forth banter. Seems kinda out of place though
Willem Dafoe is playing Kent Nelson. I saw the helmet the other day on set. It's on Kent's shelf in one scene. They're planning on suiting him up fully for JL Part 2 (more on that later).
The second Justice League film will have many of the lesser known League members joining up. They want to create a huge team of members to include whenever there is a global threat. That way, fans can get hyped and hope that they bring in the rest of the League for future movies. Other heroes they're considering now are Blue Beetle, Zatanna, Martian Manhunter, Booster Gold, Plastic Man, Raven, and some others.
The only hero brought in for Part 2 that stays a, main member is Green Lantern, who will be Hal Jordan (John Stewart might appear briefly in Part 2, still discussing that).
The Cyborg movie is up in the air right now. Lots of talks about making it into a Titans film instead.
Zack Snyder is NOT being booted off any upcoming movies. I've seen a few petitions online concerning that. Everyone I've talked to about this knows about it and is worried about this movie. Snyder is focusing on visuals again but the story is way more coherent this time in my opinion.
The Justice League Dark movie is NOT dead at all. I heard they're going to have a huge announcement about it at Comic Con this year. The goal is to make everyone forget about Marvel this year and reel people back in after the failure of BvS.