static friction or kinetic friction?? Urgent!!!!

(a) How can i find the friction that exerts when the block is moving?
Note the angle the inclined plane makes with the horizontal, say t. The sliding force along the inclined plane is mgsin t = 400sin t. Since it is moving at a constant speed, this is equal to the friction acting on the block.

(b) When i find the coefficient of friction of this situation, the coefficient of friction is static or kinetic?
The relationship between the coefficient of friction u and the normal reaction N is,
Friction = uN and N = mgcos t.
So u = tan t
Since the block is still moving, it belongs to kinetic.

(c) How can i find both kinetic and static coefficient of friction of the situation?
When the block is at rest, tilt the plane slowly until it just starts sliding. Note the angle of inclination, say ts. Then find the coefficient of static friction by tan ts. The coefficient of kinetic friction has been obtained in Part (b).

(a) the friction, you may know already, friction coefficient times force perpendicular to surface.
(b) your situation, constant speed: hence no force, it should be static friction coefficient.
(c) by experiment.