1) The document discusses several factors that determine interpersonal attraction including physical attractiveness, proximity, familiarity, similarity, and reciprocity.
2) Physical attractiveness is influenced by features like symmetrical faces and hormone levels, while proximity and familiarity increase liking through mere exposure and similarity effects.
3) Relationships range from initial attraction that can develop into lifelong friendships or romantic relationships like marriage. Friendship provides companionship while loneliness is associated with negative emotions.