What is the most appropriate statistical test in this situation? Why?

Are there significant differences in the number of deliveries?

If the goal is to promote repeat business, should the discount be continued?

Which type of correlation procedure would be most appropriate to gauge the relationship between each pair of variables?

Do you expect each pair of variables to be significantly correlated or not? Why?

For the variables you expect to be significantly correlated, what do you expect the direction of the relationship to be? Why?