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 fftifft segments. If you have only a single fft segment (from your FFT analysis), then there's no need for (W)OLA at all.
Yes