The usual response to Question #1 (why place the tree where Adam and Eve could reach it?) is to invoke the notions of temptation and free will. However, neither of these work in this context.
The Christian God is all-knowing, all-seeing, and is everywhere. So not only did he know they would eat from the tree as soon as he placed it, he knew the exact circumstances that would lead to the fruit being eaten. Where, precisely, is the free will? Simply put, one cannot be all-knowing and not know something. So I fail to see how free will enters into this story, or in fact, any of the Christian world.
As for temptation… invoking temptation on innocents, while enforcing a harsh punishment when they inevitably succumb, is just sadistic. The bible says that Adam and Eve only gained knowledge of good and evil after eating from the fruit, so they had no framework on which to place God’s command not to eat. His words would literally hold no more power than the wind to them.
– – – – – – – – Question #2 – – – – – – – – – – –
Before eating from the tree of good and evil, Adam and Eve were innocent. So why punish them so harshly for disobedience? That’s like putting a two-year-old’s favourite treat before them, telling them not to eat, before leaving the room. Then, when they innevitably eat it, you send them to maximum security prison for the rest of their life.
So, why did God feel it neccessary to punish Adam and Eve so harshly for something that (1) he knew they would do, and (2) they basically had no control over?
Insight and longevity.