WOLA vs Simple Hamming Window on signal before FFT
I'll try to briefly answer your questions.


No, WOLA (weighted overlap and add) is applied directly on the result(s) of an inverse FFT operation. The IFFT results ( time segments ) are first multiplied by a particular window function (e.g Hamming ) and then overlap-added to produce the final time domain signal ( waveform ).
As explained in #1, WOLA is used to generate a time domain signal from multiple, overlapping ifft segments. If you have only a single fft segment (from your FFT analysis), then there's no need for (W)OLA at all.
Yes