1. Satan's first lie on earth was a half-lie. He did directly contradict God in 'you shall not surely die'. But now the conversation had turned from what God said, to what Eve said, and so as pertaining to 'neither shall you touch it', the serpent was correct that they would not surely die. The devil's subtilty is half-lies and half-truths. If he had just come out and plainly said you will not die for eating it, they would have most likely rebuked him for it.
2. I believe it is all important for believers to understand that the first transgression, Adam's transgression, was proceeded by the first error of ministry. Yes, we are warned not to transgress God's command, but I believe it is clear that much transgression by believers is a direct result of false ministry. False prophets, apostles, teachers, and christs have been the greatest source of destruction in God's house and church, with the most amount of condemnation and warning from God. Afterall, she is called Babylon 'the Great'.
The first half-lie of the devil on earth was preceded by the first half-truth of the woman. The question before them was 'what did God say'. The answer of 'not eat of it, neither touch it' was only half true. One of the two, apparently Eve, added to His commandment 'neither shall you touch it', and the serpent had her. He used her own words against her. She then proceeded to transgress His commandment, not by touching it but by eating it. Why did she eat it in direction contradiction to God's command? Perhaps because she saw there was no death in touching it, and she believed 'not touching it' was part of God's command; therefore she was able to believe God must be lying also about not eating it.
I believe that when Eve reached out to take hold of the fruit, she was testing God's Word on the matter by touching it first. No death there, so no death in eating. That is the real danger of adding our, or others' own personal rules and things to God's Word, as though God actually said it Himself. Afterall, we are supposed to be living by faith in God and His Word. If we believe a lie about His Word, then our faith in Him will be corrupted, and our living for Him will then be corrupt. If we are living by faith...
I call it the sea-saw effect. If you add to, you will take away, because what goes up must come down.