The total number of points in a resort cannot change. In other words, legally DVC CAN increase the number of points required for a given night, but in doing so they would have to make an identical decrease elsewhere on the calendar. You'll occasionally see people refer to this process as "reallocation" of a resort's points.
In the 16 year history of DVC points have only been reallocated once--that was back when there was just one DVC resort. It's possible that we may see other adjustments made over the years, but it's not going to be a regular occurrence and the changes would likely be minor.
EDIT: To be clear, the above applies only to the 8 DVC resorts. The nightly point requirements for things like the Disney Collection (cruises, non-DVC hotels) and Concierge Collection CAN and DO change annually.
Incidentally, when your Guide referred to getting approval to answer your question, I believe that he was specifically referring to responding to you in writing. Depending on who you talk to, DVC Guides are either highly discouraged or all but prohibited from corresponding with people via email. The reason for this is simply because doing so has a great potential for liability from DVC's standpoint. If a salesperson were to misrepresent some portion of DVC--even unintentionally--that email could end up being the basis for a lawsuit against DVC. That's not to say that anyone would intentionally misrepresent what you are buying, rather it's just reflective of the fact that some people will invariably describe things in clearer terms than others.
I'm sure you will get proper answers to all of your questions if you set aside a few minutes for a phone call with your salesperson. But should you decide to move forward, remember that the Public Offering Statement (POS) and other printed program guidelines are the only things that truly matter. Read those documents carefully so that you fully understand what you're getting into. I don't think there are any major landmines within the docs, but they do serve as the basis for a lot of "what if" discussions around here.