Assume a task which most of us perform each day, the act of purchasing an item along with a debit card. A card and the Personal Identification Number (PIN) are utilized. Generate a list of at least 10 confidentiality, integrity, and availability requirements which should be met for this transaction to be secure (like secrecy of PIN, or possession of the card), and state the level of significance of each requirement. Recognize any potential vulnerabilities in the act of forming a purchase along with a debit card.