With regard to your first question about the psychological processes of interpersonal attraction there are (at least) 4 factors that have been found in the social psychology literature.
- Contextual Aspects.
People are more likely to develop attraction
towards those they see more frequently than others. This is known as
the Mere Exposure Effect (Saegert, Swap & Zajonc, 1973).
- Attributes of the Target Person.
The perceived attractiveness (for example of the
face) is another factor. The comments point to resources regarding
- Attributes of the Perceiver.
Mood has an effect on interpersonal attraction. Being in a positive mood makes a person more likely to develop attraction (Gouaux, 1971).
- Aspects of the relationship between Perceiver and Target Person.
Perceived similarity has an effect on interpersonal attraction (Byrne, 1971). Similarities can serve as a positive reinforcement of the attitudes of the perceiver.
They are also the foundation for common activities and also which in
turn lead to closer relationship.
Byrne, D. E. (1971). The attraction paradigm (Bd. 11). New York: Academic Press.
Condon, J. W., & Crano, W. D. (1988). Inferred evaluation and the relation between attitude similarity and interpersonal attraction. Journal of Personality and Social Psychology, 54(5), 789.
Gouaux, C. (1971). Induced affective states and interpersonal attraction. Journal of Personality and Social Psychology, 20, 37–43.
Saegert, S., Swap, W., & Zajonc, R. B. (1973). Exposure, context, and interpersonal attraction. Journal of Personality and Social Psychology, 25(2), 234-242.