Fall of Man?

Adam and the woman were thrown out of the Garden in Eden because they disobeyed God and ate the fruit of the Tree of Knowledge because the snake (which was Satan) tempted the woman.  

Questions:   

1. How the hell was Satan able to enter the garden in the first place? If this god can order an angel to guard the entrance of the garden with a flaming sword, why did he didn't employ this before Satan entered his playground? Does that mean Satan just outwitted god?  

2. If god is all-knowing, he already knows that  Satan is inside the garden. So why did he not able to remove him? Being all-knowing, he already knows what will happen.   

3. Being all-knowing, god already knows that Adam and his mate will be tempted by Satan to eat the fruit of Knowledge. Being omnipotent, what did god do to prevent this from happening? He already knows what will happen, right? Can't this all-powerful god make an unpenetrable fence around the tree or even a simple picket fence?   

Typical Christian response: God is testing Adam.  

Me: Test? Wait? If god already knows the outcome why does the need to test the subject? Would it be better that he made some kind of prevention since he already knows the outcome?   If god already knows the outcome yet didn't even make any attempt to prevent it from happening even if he has the capacity to do so then that makes god more responsible for letting the world become corrupted since Adam and the woman are innocent.   

It's god fault!