This might be accurate at a specific lounge or set of related lounges, but in general you do need your Priority Pass card -and- the lounge attendant has no knowledge of the details of your membership. The attendant records your visit, the number of guests, and if there is a charge it will appear automatically on the associated credit card.
True but 4/5 times, they just ask the card origin and said it was fine.
The guest restrictions displayed on prioritypass.com pertian to purchased memberships. Memberships sponsored by credit card issuers may have different guest charge arrangements.
The Canadian Amex Platinum will let you + one guest free of charge or you + spouse + 2 kids free of charge. Any person on top of either combination is $27USD.