Should I make custom ad targeting with Admob?

Hello,

I have just a quick question: I just started playing with Admob for my game and for the tutorials i have found they all use custom add targeting. So in the script they specifically write which audience this app is targeted for. Something like this for example: return new AdRequest.Builder() .AddTestDevice(AdRequest.TestDeviceSimulator) .AddTestDevice("0123456789ABCDEF0123456789ABCDEF") .AddKeyword("game") .SetGender(Gender.Male) .SetBirthday(new DateTime(1985, 1, 1)) .TagForChildDirectedTreatment(false) .AddExtra("color_bg", "9B30FF") .Build(); This seems kinda against the whole idea of ads which should be able to find its own audience, or should you explicitly write this?

Question 2: How does a banner app from admobs work: Do you earn money the longer it is visible? or do you only earn money when it is clicked?

THanks Andy