I am an experienced Android developer. My experience in Android development is over 3 years.
I have some clarifications though.
1. What are you trying to achieve ?
2. Open other Apps, what kind of apps are they ? Are they your Apps ?
3. Yes, we can track record of every ad click and impression.
4. How can user get money ? If user clicks Ads, you will get money. If you are saying exactly what I think, then you are crediting user with some money to the wallet. And user can withdraw that money. Well withdrawal can mean many things. What kind of withdrawal are you trying to convey ? I'd rather say transfer money to the wallet instead. It should be "wallet for transfer of user's earning" I think.
On clearing these requirements, I can help you out with this.
Just reply back, we can discuss further on this.