Thank you so much for liking the game. ^^
As for your questions, of course 18+ content will be on Android too, once there is any; there won't be a difference in content between platforms. Though I most likely will have to focus on the desktop versions first, since the Android port still causes some trouble and will have to get optimized properly.
There are going to be four love interests, if verything goes as planned. ;3
Since a release date is still some time away, I can't say yet if it's going to be free at completion. The next updates will be though. :3