SMW -- no worries -- you're of course free to take whatever advice you want. I wasn't sure if you've been communicating with Ruby or the others this year, but I know a lot of alums forget that they can still use these services even after graduation.
As for having the advisors find out for you -- look at this way, if you are seriously considering trying to reapply while you have deferred Columbia, you are going to need to make sure you can do this without jeapordizing your Columbia spot, one way or the other. You've already been accepted to Columbia -- I'm about 99% sure they can't reject you at this point for asking a question. If you email Frantz personally, you could even just make it sort of vague, like "What are my responsibilities by deferring -- any additional paperwork, anything I can or can't do, etc." Also, I'm sure you're not the only Stanford student who has been accepted to Columbia -- if Ruby or someone emails for you, they can just pose a hypothetical -- "I have a student who is considering attending, but wants to know about your policy on deferrals." They might think it's you, but again, THEY'VE ALREADY ACCEPTED YOU. The worst case scenario is probably that they would say they don't want to grant you a deferral after all. I think this concern about "Make sure that Columbia doesn't find out your asking about this" <img border="0" title="" alt="[Eek!]" src="eek.gif" /> , is a little over-dramatic. Since YOU'VE BEEN ACCEPTED, it seems really, really unlikely that they would rescind your acceptance because you asked a question. If they don't want you to do it, they'll be really explicit that you aren't allowed to reapply while deferring their acceptance and then let you make your decision.
Anyways, the best first step is probably to call or email Ruby or Verity -- they can either answer your question directly, or advise you if you could possibly incur some kind of wrath from Columbia by inquiring about this further. Again, I really doubt it, but the advisors should give you definite info.