I would also point out you started off by stating from a financial perspective, but at this point I highly doubt your college would give you a penny back since you have been in classes for @ 7-8 weeks and will be coming up on mid-terms anyday now. Thus, the idea of cost saving would be moot.
I would also check with admissions if you drop Stats, because it may appear on your transcript as dropped no grade, and at some schools this can impact your cgpa, because a drop is different than withdraw. I know for our 2 kids you have only 10 days before they change it to drop, and that goes on the permanent transcript.
Your transcripts will arrive way before you do because if I recall correctly your college ends the 1st week of May...almost 3 months prior to you reporting.
If you are having trouble with Stats get a tutor, turn off the Xbox and crack the book over and over again, heck sleep with it under your pillow too hoping osmosis will work.
USMA from an academic perspective is an Ivy. As others have stated by staying in these classes you only gain, if not from a validation position, but personally from an academic perspective it will be easier since this will not be new material, whereas for many of your peers this will be new.
xposted with 845.
As far as the Cadre, I know at our DS's AFROTC det. they are officially informed of the appointment because they are a nominating source. I do agree that out of respect go in today and tell them personally of the appointment and your decision to accept it.