How often does Pardot sync with Salesforce?

How can an admin find the number of mailable prospects in their database?

A prospect believed to be on an engagement program did NOT receive an email. Which three troubleshooting steps should an Administrator take to determine why the prospect did NOT receive the email? (Choose three answers.)

What must happen in order for a newly created lead record in Salesforce to be created in Pardot immediately? (Choose two answers.)

A custom redirect has a completion action to add a tag of "clicked" to all prospects that click it. An unknown visitor clicks on the link and then fills out the form as Bob. A prospect also clicks on the link and fills out a form as Kate.
Which three things will affect the prospect records based on these activities? (Choose three answers.)