[Hadi379]

On the first question, I'd be willing to bet your running a roughing process for the bearing hole and it needs a finishing process to remove the remaining material.

In the second scenario, I've experienced this quite a bit on my tormach. I would either use a deburring tool to remove the foil, or set my zero for the Z axis a tad bit lower than actual zero. This happens sometimes based on how the workpiece is clamped down, which can cause the material to bow in the center, or pick up on one end.