(4) Kant's larger claim here is that we all need to focus on our own spheres of control, make sure that you do not lie, make sure that you do not steal etc. If we do this, we will all have autonomy. (Because morality comes from our own reason, following reason is what it is to be autonomous). (5) A critic of Kant could reply that in so far as the consequences are predictable and forseeable, then we are accountable for them, an they are within our control.
(2) This part of the 'clashing virtues' objection is somewhat resolvable. While we are obligated to follow perfect duties at all times, imperfect duties are more lenient.
(3) The apparent requirement to lie here seems counter-intuitive. HIs fundamental point seems to be that telling the truth will have bad consequences. The moral value seems to reside in the consequences, and not in whether the maxim is universalisable.
(1) Consider the mad axeman case. Kant would say that it is wrong to lie in this instance, Lying cannot be universalised, as truth as an institution is undermined if 'It is acceptable to lie' holds true. Therefore we have a perfect duty to tell the truth. However, we also have an imperfect duty to care for others.
Kant's deontological ethics are often criticised due to his tendancy to contradict consequentialism, which many view as common sense. In the axeman example, it is the consequences of having x as a law (in his second formulation) which make it immoral. However, Kant claims that his ethics are purely motive-based.