I played more than just "play now" games. There were online servers available for dev team members and gamechangers to play one another.
Every game mode that currently existed in the beta version they gave to us I tried for at least one hour to see the changes. Of course, the modes that never interested me (i.e GM, Be a Pro) I spent less time playing.
No, enforcers cannot still deke like Datsyuk.
I did notice changes in defense and defensive gameplay.
Player separation - not sure how I can answer this.
There is more physicality aside from big hits.
Goaltenders were improved in my opinion.
Edit player - Not sure if I'm allowed to answer this or what not.
This game is more than just the features of last-gen NHL 14 transferred to a new gen version. I cannot announce these game modes at this time. Wait for EA.
This game should not be called HUT 16.
Hope that helps.