The first part of the Road to Independance pretty much will be a tutorial. It's true that the RTI campaign isn't just a tutorial however. And yes it has been confirmed you play as the US. The first chapter is you playing as the British colonising the new world. The second is Britian vs. France and the Native American tribes. In the third chapter you play as the US colonists and attempt to throw out the British.
Yes I believe this is confirmed to act in place of the tutorial,

what is not yet confirmed is if I will have a attractive female blond advisor yet again