Q1. Please tell me how to count when Count Input is set to Disable. I think the counter will change its count on every input clock edge.
Yes it is correct.
Q2.It is described in the data sheet as follows "if this input is configured for level sensitive, the counter will change its count on each pre-scaled clock edge."
If so, at the level setting, the change in count value will not depend on count input. Is this recognition correct? If it is incorrect, please tell me how the count input influences the change of count at the level setting.
This is correct. But this will apply good only when the count input is active (high). If it is low count would not increment based on the clock input.