You're right, personality does not stick in 100% of people. However, according to the literature, personality traits (or at least the manner in which it is conceptualised in psychology, with the 5 "core" domains being openness to experience, agreeableness, extroversion/introversion, conscientiousness and neuroticism), have been shown to be relatively stable throughout most people's lives. Although you've included a little essay there on how situations can impact on a person (which I admittedly have skimmed rather than read), you did not mention that one's outlook and personality also affect how you interpret certain situations and the manner and degree of how one changes. The relationship between personality and one's environment is more than a one-way street.
I think the initial question, Looks vs Personality, is somewhat misleading (or at least the way I interpret the title of this thread); the question posed isn't an 'either-or' question. For most people, both factors contribute to how they feel about someone. For example, in the case of looks, most people are more inclined to judge attractive individuals or the people associated with them as having more positive qualities. On the flipside, finding someone you can relate with can help you overlook their flaws, sometimes to the point where the overlooking gets completely out of hand - scientists call this disease "love"