How to do parayanam on Shrimad Ramayana? Should it be done after partaking food or should it be done after the performance of Sandhyavandanam? Should it be recited for seven or nine days? Or should it be recited for one whole year by reciting 1 or 2 chapters per day? Can we recite during the menstrual time of women at home? If a day’s recital happens to end with the sargam that describes Sita Piratti’s weeping, can we conclude with that or must we conclude by reciting other sargams?

If you recite Shrimad Ramayana for the pleasure of Bhagavan, then you can recite after partaking of food; if it is done for a material purpose then one should recite before partaking food.
Not necessarily that it has to be read in saptham or navaham, for each day one sargam can be recited.
There is no connection between a menstrual time and recitation, you can continue with the parayanam at a room where they are not present.
Generally, those who recite will not pause during Dasaratha Niryanam and his Samskaram but there is also practice of reciting 5 sargas every day where one has to pause at this phase but there is no harm in pausing during a sorrowful event.