Kant does not regard freedom as an item of faith because it is too basic to our agency to be related to any end.

Virtues consist not only of acting in certain ways, but in ways of caring and feeling.

As I understand it, Kantian constructivism is partly a position in normative ethics and partly a position in metaethics. In metaethics, it is the position that ethical claims have truth values, but their truth conditions consist not in a set of objective facts to which they correspond, but instead in the outcome of some procedure of deliberation resulting in decisions about what to do.

We can establish empirical criteria for free actions, and investigate human actions on the presupposition we are free.

From the beginning, there has been a tension in the reception of the Kantian idea of autonomy. If you emphasize the 'nomos' (the law), then you get one picture: the objectivity of ethics. If you emphasize the 'autos' - the self - you get the idea that we make the law. Kant never hesitated in his choice between the two emphases. He emphasizes the nomos (the universal and objective validity of the law).

Kant thinks we can show that there is no contradiction in supposing we are free.

I think the term "Kantian constructivism" as an oxymoron. Kant was a constructivist about mathematics, but not about ethics.