For q4 and 6, I used to struggle with those as well but I finally got my head around it (I think, havent got my SAC back yet lol)
Initially, there is a downwards north flux. When the coil is removed, we have a change in the north flux (I just call it that, but the polarity is important) in the upwards direction (because the flux is decreasing). To oppose this, the coil induces a current that will create a downwards force, which is clockwise when viewed from above, and I think you know how to find the magnitude of the current judging from your question
As for question 5, D is incorrect because while there is a change in flux when they change the direction of the magnet, this change is only temporary and the system kinda becomes used to it (its like using a DC battery for a transformer- there is only a temporary change in flux). When the coil is removed, the same emf is generated in the coil as when the magnet was in the original orientation, just in the opposite direction.
I dont think they would ever ask you what would happen if it was being changed simueltaneously, because the only way I can think of doing it is to graph the flux and then derive it to find the emf, which is outside the scope of the course (I could be wrong though)