Q: "Are honesty and sinlessness the same thing? Is the call to honesty exactly the same as the call to repentance, or is honesty a higher form of repentance (similar to a distinction between sins of commission versus sins of omission)?"
A: I would not call them the same. I believe honesty is a part of repentance.
Q: "Are you hoping to reach a different or wider subset of people with this book than you were with the repentance book?"
A: Those would be wonderful outcomes, but the main purpose is to help people more clearly see how they are, how they could be, and what they stand to gain if they improve through giving them eyes to see what was hidden to them before, as well as to enable them to help others with the same.
In Joy on Purpose, I described the Life Plan framework. Jesus has a life plan. He has character qualities. We are supposed to learn what those are and adopt them ourselves. One of them is honesty, and I believe the book I wrote describes the Lord's honesty better than any other book I am aware of. I hope that through it others can understand more of how the Lord is and find better reasons to become that way themselves.