Input biasing and coupling calculations
Here's the problem with your question...

Say you chose a high-pass cut-off of 3 Hz and fed in 3 Hz. The signal at the inverting input would be 3 dB down on the original signal level. Let's say you had 1 volt p-p and this dropped to 0.7 Vp-p after the filter. That would certainly trigger the comparator to produce a decent enough output square wave.

Now let's say the input frequency was 0.3 Hz - the signal at the inverting input would be 10 times lower at 100 mVp-p and it will still produce a decent square wave output from the comparator.

Where does this end?

If you dropped the frequency to 0.03 Hz, the signal after the filter would be 10 mVp-p and, for a lot of decent comparators, an output square wave would still be produced!

In other words, your idea about filtering the signal is meaningless until you apply hysteresis to limit the size that a signal can drop to whilst still producing a square wave from the comparator.

So, to ask this question you need to specify hysteresis levels, inputs level and what noise you have on the input. Basically, the best answer would be to use a simulation tool.

Go and use a sim tool and add hysteresis and trial it with different levels and see the problems and uncertainties.

But, to answer your edited question, C2 and R4 define the 3 dB point of the high pass filter, fc = 1/(2\$\pi R_4C_2\$). You can largely ignore R3 because C2 will be much more dominant at the low frequency end of the spectrum. But, there's no better answer than a sim other than to build it.