[Help] Facebook Ads Install

Hi
I am young Android Developer and i have published some Games in Google Play. But my Games still have little amount of install. I want creat campaign for advertising in Google Play but i dont have CPI, still use CPC. Please help me
And other question : If now i could use CPI, what is true : Customer click on Banner and Facebook track Install or Click on Banner, move to CH Play, Install and Facebook Track Install
Thanks