Let me answer your second question first: For each Use Year, the member owner must notify Member Services if they wish to opt out of their fixed week. They can opt out as early as 11 months before the date they wish to use the points or as late as the day before their fixed week is scheduled to start. For example, let's say I own a fixed week at Aulani that starts on Sunday, May 18, 2014. Rather than going to Aulani for that week, I want to go beginning April 10, 2014. I can call MS today and opt out of my week and convert my week to Aulani Home Resort DVC points. Then, tomorrow, when the 11-month window opens for trips beginning April 10, 2014, I can book my stay (based on availability).
If I needed more points for my April 10, 2014, stay then I received by converting my 2014 fixed week, I could opt out of my 2015 fixed week at the same time I opt out of my 2014 fixed week. Then, I could borrow some or all of my 2015 points into my 2014 Use Year and apply them to my April 2014 trip.
I can elect to opt out of my fixed week within 31 days of the start of my fixed week. However, the points I receive would be placed in Holding Status, meaning I could only use those points to book reservations with check-ins no more than 60 days in the future. This is like any other DVC reservation that is cancelled within 31 days of check-in.
By the way, I should point out that fixed week owners, just like traditional points owners, have a specific Use Year attached to their points. When the fixed week is converted to points, those points have the same Use Year as all other points in the Unit from which the points were derived.
As you see, the fixed week owner is afforded much of the same flexibility as DVC members with traditional points.
Now, for your first question: A fixed week owner pays a 10% premium to purchase a fixed week. In 2012, a one-bedroom Ocean View during Christmas (Premier Season) costs 434 points. The cost of a fixed week for Week #52 is 477 points, which is 43 points (10%) above the cost of the traditional week. If a Fixed Week owner opted out of their fixed week for Week #52 in 2012, they would receive 434 points.
I know that Fixed Week owners are immune to
point chart reallocations. If in the future Aulani's point chart is reallocated and the Premier Season rate goes up from 434 points to 452 points, the Fixed Week owner does not have to pay more for their week. However,
I don't know if a Fixed Week owner who converts their week to points gets the reallocated number of points (454) or if they are always limited to the original value of 434 points. I suspect it is the later, but I don't know.