Yes, the applied voltage affects the impedance, which can be used to gather information about the material's properties or system being n g studied. It is essential to choose the appropriate voltage range for the EIS measurement in order to accurately reflect the behaviour of the system being studied and to avoid damaging the system or electrode.
The voltage you apply is an external force which you give to your electrode in order to examine the electrochemical properties. So the ac voltage supplied to the system will create an environment with different frequencies. So the frequency dependence also plays role along with the applied bias to the electrode.
It would be better if you could define your system, application and applied bias window which you use to analyse your other electrochemical techniques of your system.
Yes it can affect the EIS measurement. EIS is a non-destructive technique; therefore, a small applied voltage should be selected during this measurement to ensure that the sample is in the save range and the applied voltage does not generate extra charge carrier within your sample.
Yes, voltage affect the EIS measurement. In principle what you are doing in an EIS measurement is a sweep. So you want to be sure you are sweeping in the range of voltage suitable for your material.
Now you ask how to know the appropriate voltage, you know that from a CV. A CV will give you information about the potential of your material relative to the current. In the case of pseudocapacitors@ or a redox-active material, it also help you to know the redox potential of your material.