Witch-slapped: Macbeth's fall from grace

Question 1: Why do people who are not "evil" take the first step into evil? What, for instance, is involved in taking that first step "down the primrose path to the everlasting bonfire" (Macbeth, 2.3)? What are the consequences of the individual choosing evil (particularly the internal consequences)?

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In my opinion, I believe people who are not "evil" take the first step into evil because they are either pressured into it or curious about what the other side entails. The first step into evil could be anything from stealing to lying to cheating to murder. In Macbeth, we can see that Macbeth's first act of "evil" is his decision to murder King Duncan. It is no doubt that Macbeth was pressured by Lady Macbeth to kill Duncan, but could there be another reason behind his decision? In the beginning of the play, Macbeth meets the Weird Sisters (three witches) and they tell him his prophecy of becoming king. The second witch says, "All hail, Macbeth! Hail to thee, thane of Cawdor!", then the third witch says, "All hail, Macbeth, thou shalt be king hereafter!" (Macbeth, 1.3). Macbeth continues to think about this prophecy and becomes determined to make his prophecy come true. This leads him to do pretty much anything that will give him more power, including murdering anyone who stands in his way of the throne. 

The consequences of any individual choosing evil include getting sucked in to evil ways, getting caught and punished for his/her actions, and if he/she is actually a good person, feeling guilt or remorse all the time. So far in the play Macbeth, we have seen Macbeth feel guilt, yet continue to act evilly. Right after killing Duncan, Macbeth is talking to his wife and says, "I'll go no more: I am afraid to think what I have done; Look on 't again I dare not" (Macbeth, 2.2). He knows what he just did was wrong, but tries to ignore it because he doesn't want to face it or deal with any repercussions it might have. 

I think Macbeth is a good example of why choosing evil can be so bad. At the time, it may seem like nothing too horrible could come out of murdering one of your good friends to become king, but in reality, it can lead to a lot of other problems. This one evil action of Macbeth's created sort of a snowball effect, and Macbeth couldn't help but continue to do evil things. Although Macbeth got what he wanted (to become king), I think the consequences weren't worth all the trouble he went through.