Yes - one or the other. Can't combine those two - it will give an error if you try to apply a second one. You *can*, however, click through to the Gift Card site via a cash back link and stack up to 5% cash back upon either of those two promos.

5 points per dollar on the card when you either purchase the Gift Card or when you pay for the stay (forgoing the Gift Card bonuses). 10 points (or up to 15 if you have status) per dollar spent for your actual stay... nothing to do with payment method. Another 10 points OR 10% bonus when you buy the Gift Card using a promo. Another 5% (using TopCashBack) when clicking through a cash back provider to make that Gift Card purchase. Finally, another 4% (using Mr. Rebates) when you reserve your room by clicking through a cash back site to book (not valid with non-commissionable rates, such as corporate ones).

For the $400 Gift Card alone, ignoring actual stays you'll use it for, you'll get 4,000 MRPs OR a $40 (promos), AND $20 cash back via TopCashBack, AND another 2,000 MRPs for buying with the Chase card. All together, 6,000 MRPs and $40.

For the stay, you'd get 15 MRPs/$ as a Platinum for 6,000 more MRPs, plus another 500 MRPs as your Platinum Arrival Gift (should you choose), plus another $16 cash back if you book using Mr. Rebates.

Everything together = 12,500 MRPs + $36 cash back on $400 spent. If you value your MRPs at 1 CPP, that's a $161 return on a $400 outlay, or about 40%!

Almost certain you cannot. You *can* use them to pay for a reservation of a timeshare property (MVC), but if you are an owner, I'm almost sure that you can't apply it to maintenance fees.