I had faced the exact issue where 1 ticket was confirmed and other ticket is in w/l 6 and we were allowed to board the train and berth was allocated based on availability. Hence do not worry if any partial waiting list tickets.
No, there isn't any way to book it without disclosing the gender. There are a number of reasons to make it mandatory:
There are a lot unauthorized agents which make generic/fraudulent ticket bookings and then illegally resell these at higher prices. Asking specifics like age, gender, name, etc. prevents such practices to an extent.
There is a Ladies Quota ...