Zendaya's character in Homecoming is "Mary Jane." Saying she's "MJ" but not "Mary Jane" is dumb.
The change I would make hasn't happened yet. Don't be afraid to recast the big guns and continue the current continuity with the timeless heroes. We all love RDJ, but other actors can, in fact, play the role and make it their own.
I like this. One of the things I think that they ought to have done with Marvel's Agents of Shield was to use it as a promotion for the films and vice versa. After a film, leave a few loose ends that becomes a major plot in AoS (they did that pretty well with the back half of Season 1 and Captain America: The Winter Soldier's Hydra reveal; they dropped an opportunity on that with the monster running amok at the end of Thor: The Dark World). Leading up to a film, introduce a few goodies in the series that become a plot point or key McGuffin in the film (the Asgardian Angry Staff from Season 1 of AoS could have been used to introduce a character like The Wrecker).