It was just the core four as they answered questions from the moderator and audience. The following is a paraphrase of their answers. No real scoops since the writers are still writing
-KJ would like to see Sabrina on the show, whereas Camila and Lili seem to think the cast is big enough. Cole thinks its nice that recurring characters (like Kevin) are getting more screentime/focus this next season
-Next season, Veronica will have tension with her dad, and the show will also play with the classic "Hiram hates Archie" dynamic
-Lili doesn’t use the comics for her portrayal of Betty because she doesn't like how much of a doormat she is. Cole on the other hand would like Jughead to be more removed from the group and weirder like he sometimes is in the comics. He compared Jughead to L from Death Note. He also thinks Jughead is most like a dog because of how whipped he is.
-When asked what other character they would want to play, Lili said female Jughead, Camila said Betty, Cole said Reggie, and KJ said Kevin.
-When asked about kissing Cole: “FAANNtastic but I liked kissing Cami better, what?” When asked about shipping, Cole comments on how shippers want the actors to weigh in on ships to fuel their online wars, but he's never going to give a serious answer about what he ships on the show.
-Cole insists that the "I'm a werido" meme doesn't bother him
And here's a random fan picture so you can see what they wore if you care about that
And also, a week ago Madchen posted a behind the scenes of some of the cast filming promos for season two. Unfortunately, they're just walking through dramatic mist rather than wading through real water, but I'm sure the CW will slap some neon colors or do something overly dramatic in post.
source that summarizes talking points
Instagram pic source/ Madchen's post