I'll just add that on one occasion I asked the CS reps whether I could use the 1-4 Cert for a CAt 5 Pointbreaks hotel, as they are the same amount of points that are required if one were withdrawing points from one's account and the answer was still no.
So, all the above permutation will likely be rejected - 5th night free does not apply to using an award cert in lieu of points withdrawn from one's account.