Answer to Question 1
A check is overdue 90 days after its date. When an instrument is overdue, a recipient is on notice that it may have a defect. The UCC states that a holder in due course is a holder who has given value for the instrument, in good faith, without notice of outstanding claims or other defects. If a check is marked Insufficient Funds by a bank, it has been dishonored. No one who obtains it afterward can be a holder in due course.
Answer to Question 2
B