What is the connection between product attribute sets and categories?

The constructor function for \Magento\Catalog\Model\Category contains this excerpt:

With the automatic dependency injection that Magento provides, how is the StoreManagerInterface resolved?

Magento 2's architecture uses code to bootstrap a custom module that resides in app/code.
What two files are required to make a module usable? (Choose two.)

In a code review of a merchant's site you have discovered that there are multiple observers for the
checkout_submit_all_after event. After closer inspection, you notice one of these observers is relying on the
others being executed before it is called.
What risk does this pose, and how can it be mitigated?

You have configured an event observer to watch the checkout_submit_all_after event using this XML:

What is the required class definition for the event observer?