Not only in order to act morally, but even to formulate theoretical questions, devise experiments, choose which ones to perform and what conclusions to draw from then - we must presuppose that we are free. That's the sense in which it is true that for Kant "we must assume we are free."

It would be nice, wouldn't it? if we could get comfortable about the problem of freedom. Kant thinks that we can't.

I think it is clear that what we ought to do has to be independent of our decisions about what to do, and independent of any procedures we might use in making such decisions.

As with many metaphysical and religious questions, Kant thinks they lie beyond our power to answer them. If you can't stand the frustration involved in accepting this, and insist on finding some more stable position which affords you peace of mind and intellectual self-complacency, then you will find Kant's position "problematic" in the sense that you can't bring yourself to accept it. You may try to kid yourself into accepting either some naturalistic deflationary answer to the problem or some dishonest supernaturalist answer.

Leaders of nations, and people whose wealth or fame gives them power over the lives of others quite often do more harm than good.

Kant considers belief in God and immortality to be items of "faith" because he relates faith to the pursuit of ends - in this case, the highest good.

Empiricist philosophy always tends to be anti-philosophy (and is often proud of it).