How to obtain the Sound Pressure Level from .wav file based on these given parameters?
The hydrophone has -180 dB 1V/uPa or -60 dB V/Pa. 1 Pa produces hence 1mV or, other way around, the sensitivity is 1mV/Pa. Peak voltage is 5.64 peak to peak. That's 2.82V peak or 2V RMS. 

A full scale sine wave has 2 V RMS which is 2000 Pa. dBSPL is referenced against 20uPa so 2000 Pa is equivalent to 160 dBSPL. 

The clipping point of your wave file corresponds to 160 dB SPL. The exact relationship between number and dBSPL  depends  on the format of the wave file (fixed vs. floating, number of bits). For a 16 bit fixed point format, the clipping point corresponds to the number 32768.