The issue is men don't use the app. I downloaded it on my SO's phone and was able to find most of the college age guys I know on it. None of them knew they were on there.
Have each of them demand a dump of their reviews from the service, as they're entitled to under EU data protection directive. If there's anything libellous in there, try to get a newspaper interested. The Daily Mail is probably a good choice for this mixture of sex and scandal.
No idea. You have to install the app on your phone, so it can read your phone's accounts. I think a Google account is required on an Android phone. Google accounts have gender in their profile (remember the G+ fiasco?). You also have to link it to Facebook, so it has access to your Facebook data as well. Maybe they don't like new Facebook accounts with zero activity, but certainly there is a usecase for women who want to use this app, but don't want to use Facebook (I would think there is a usecase for women who don't have smartphones as well). Not sure about the iPhone flow.
This thought exercise is really making me scared about how much the owners of the apps on my phone know about me!