Something out of box on freelancer.com. I like, sound like a challenge.
How about we separate tasks in smaller steps, and make deal based on these steps?
I'd need some clarification for a few items.
4- By languages, you mean languages of client app? If it is what you mean, then ok.
5- I don't see how you can contact people based on IMEI, I need a mobile number for this.
18- There is no info demographics info (age/gender/...) in whatsapp contacts. Unless either you or client user provides it in client, there will be no option for demographics filtering
Contact me if you haven't found a developer yet.