The acceptor of a bill, by accepting it -

(1) Engages that he will pay it according to the tenor of his acceptance:

(2) Is precluded from denying to a holder in due course:

(a) The existence of the drawer, the genuineness of his signature, and his capacity and authority to draw the bill;

(b) In the case of a bill payable to drawer's order, the then capacity of the drawer to indorse, but not the genuineness or validity of his indorsement;

(c) In the case of a bill payable to the order of a third person, the existence of the payee and his then capacity to indorse, but not the genuineness or validity of his indorsement.