On a class diagram, what do the multiplicities represent?

Which of the following is likely to be shown as a process in a swim-lane diagram of a library book borrowing system?

Which of the following models might include the documentation of scenarios?

A business analyst wishes to show that a company wants to store information about different types of product. Some attributes are common to every product (for example; product name) but other attributes only apply to certain product types. For example, product material only applies to accessory products.
Which of the following constructs could the business analyst use to represent this on a class model?

How would usability and performance requirements be classified?