Marketing one's product through social networks
Q: I have developed an urdu learning app and I will sell its features.
1. If I ask some of my friends or relatives to forward and market my app as much as they can to their known people, do I need to pay them for this?
2. I am a female, can I market my app by collecting a large number of emails from internet and then send my app link on those email addresses, is it permissible for me to do this?
3. I am not on facebook neither do i use it. Can I ask my friend to market my app on facebook? Is it permissible? Is facebook a haram medium to market my app? What if I dont ask my friend but still she markets my app on facebook, do I need to stop her from marketing my app on facebook?