1) Yes, the remaining OBC and cruise cash will be credited to your S&S account at the time of boarding.
2) Funds are used in this order: Non-refundable funds (non-refundable OBC and cruise cash), then gift cards, then refundable OBC, then cash/credit cards.
3) You will not be able to use cruise cash pre-cruise, since you can cancel your order for it and be refunded prior to the cruise.
4) Yes, you can use any type of funding in your S&S account to fund your player's bank. You can then cash out your player's bank at any time during or at the end of the week.
5) If you have remaining non-refundable OBC or cruise cash, you will lose it.
6) Yes, you can cancel cruise cash just like any other Fun Shops purchase prior to the cruise and receive a refund.