Howdy Caroline!
You are going to love Disney's Saratoga Springs Resort and Spa and October is such a fun time to visit Walt Disney World! Great weather, fun events and magical memories await you!
I love purchasing my Park Hopper passes prior to my vacation. It's a great way to spread out the overall cost of our vacation and allows me more money to spend on souvenirs when I arrive!
I think we are being given conflicting information. I spoke to a Cast Member at Disney Vacation Club Member Services and she told me that you can add your Park Hopper passes to your Key to the World Card upon check-in. You will be given will call numbers when you purchase your passes. After you have checked-in at your resort, proceed to the Concierge desk and they will be able to assist you further.
MyMagic+ is going to take your experience at Walt Disney World to a new level. Though official release dates have not yet been confirmed, you might get to experience the new Magic Band when you arrive. Stay tuned for further details.
I would suggest that you move forward and purchase your passes now if that is your preference. We have Annual Passes and, at this time, we do have to have a Key to the World Card and our Annual Passes as separate cards when we visit Walt Disney World. It took a little getting used to but really was not an issue. I think you will be able to get your Park Hopper passes linked to your room card, though.
Thank you for your question and please let me know if you are told different information when you purchase your Park Hopper passes. I would love to answer any additional questions you may have as you plan for your vacation. Enjoy Saratoga Springs in October and have a magical day!!