I think Walker is going to be gunning to kill all the Flag-Smashers. Whether that conflicts with Bucky and Sam probably depends on a lot of factors. ...
If you're starting Peter from the beginning and planning to go more in-depth with his progression as a teenage Spider-Man into adulthood and beyond,...
I don't know what the exact costuming situation is, but I imagine the material they use to make the Ultra suits is conducive for the actors movements...