New to Android Development

I hope this is the right forum to post this into. I am looking to get into Android Gaming Development, and of course the paid part as well (that is why I joined this site). First off I would like to say, I am not trying to make this my full time job, as I already have one. I would like to learn gaming development on the side,and hope to get extra cash on the side, but most important share my ideas to the Android Play Store. There are a few questions I have about this.

My Skill Level:
Know a little bit on:
Java
HTML
GUI (built a couple PC trainers)
3D Modeling (most with Maya, but some 3DS Max)

Was looking into using Unity 3D to create the android games. My real concern is I don’t really know where to start. Been watching YouTube videos on Unity 3D, and I have about a dozen ideas for some games/apps. Its just the advertisement on the game/app I am wondering about. I don’t want to do Micro-transactions, because I myself don’t like it when games have it. I believe you should be able to get the games fullest potential just by playing the game, not having to pay to enjoy the game.

When you have ads on your game/app do you get paid for it just being there, or do they have to actually click the ad. As well, is it 1 click, per device, per day? How does it register it, and how do I track the traffic of the ads? Like I said I really want to get into this (maybe have a couple of friends join as well) but just don’t know where to start in learning the paid side of this.

Hope you can understand what i am saying, and thank you for taking the time in reading my post.

-nick