Every main superhero character from all of the MCU films are going to be in it. No word on the Defenders or the SHIELD agents (Coulson, May, etc.), but as much as I and others would like them to appear even in a small capacity, the chances of them appearing seems unlikely.
Charlie Cox is known to have met with Kevin Feige on at least one occasion after the success of Daredevil 1 to discuss ways the character could get folded into those movies, but all of those plans went away after Feige executed his putsch in the summer of 2015 to have the studio reorganized: Feige now controls the movies, Perlmutter and Jeph Loeb control television and animation, and ne'er the twain shall meet.
As for the trailer ... wow, words cannot describe how awful that looks. I thought Civil War might have just been teething pains, but the Bros. Russo have either regressed from Winter Soldier or this is, like, a storyboard problem. I'm especially astounded at how terrible the lighting is, it's like every shot has the fullbright mode from Quake 3 enabled.