In my opinion, I think we should create a plot that kinda connects all the characters together. Of course, they don't have to be super close best friends, but at the least, we should tie in some of the characters so it's not like a total change of story from scene to scene. This way, it kinda makes it easier for the writer.
Also, I think it should be fine if we use other people's characters from time to time, as long as we're not degrading them or making them like someone else more than a friend---if you know what I mean.
And I have a question about the supporting cast: are we gonna be using the same supporting cast or totally different ones?
For me, I think we should all choose 2-3 actors and actresses and combine them for a supporting cast that everyone can use. This way, at least we'll all have some of our favorite supporting actors and actresses in our stories.