C_PTP makes the robot blend the movement, it can be parametrized through a variable at which point the robot leaves the toolpath to achieve a smooth motion. Note that it will then not exactly move through the programmed point but may take a "shortcut". In order to be able to blend movements, the robot needs to look into the "future", i.e. a few lines ahead in the code. CONTINUE allows the robot to move through the loop, rather than waiting for the robot to catch up. CONTINUE does not work for all logic types, I cannot promise 100% that it works with a FOR loop.
And regarding the other question, it depends how your axis is set up. If you give A4 simply very high limits, then you would get 100 rotations. If you set it to infinite rotation, then it won't move at all because for infinite rotation, 0 degrees, 360 degrees, 3600 degrees etc. are identical.
Best,
Johannes