Do we have to create a version for a female set plus the male one? Or can we draw just one of them?
It is your choice. You can create a Female Set "AND" a Male Set or you can just create one of them.
I have a question: Can I use a drawing that I didn't use in a previous event but posted on the forum before?
Yes you can use old creations from you. If it wasn't a winner set and if it's not already in game. So you don't must draw your old creation new.