Yes I can't wait to try it.
Oh yes yes yes yes
All I can guess is that it will be just the Inklings, and like the Villager, chose between male and female. I feel that the Octolings will be assist trophies. While I would love to see Callie and Marie, we never saw them in combat. They might be in the background of a stage based on Inkopolis, maybe similar to the Smashville stage, have a concert on certain nights.