Correlation and Regression

There is an existing hypothesis that adult attachment is related to parental responsiveness.  Adult attachment is measured by a questionnaire which assesses the relationship one had with their own caregivers and parental responsiveness is defined as how one responds to their own children when they are in need. Previous research suggests that levels of adult attachment may predict parental responsiveness. The hypothesis predicts a positive relationship.

How can correlation and regression be used to address this hypothesis?  Be sure to label the predictor and outcome variables.
What purpose do these techniques serve?  In other words, how can correlation and regression expand on this research question in a way that other techniques cannot?
Are there any limitations of these statistical methods we should cons