@tanguatlay,
Well, i hesitate to say "correctly phrased," because it can also be seen as a matter of personal style. However, this is how i would write them (trying to preserve as much as possible, the sense of what you are saying):
Sentence 1:
"Other than Nichiren Daishonin, was anyone ever born who first propagated Nam-myoho-renge-kyo?"
(That sentence has a logical flaw--only one person could ever have been the first to propagate a belief or a practice. If the purpose were to point out that Nichiren Daishonin and only Nichiren Daishonin propagated Nam-myoho-renge-kyo, then i would write: "Can anyone deny that Nichiren Daishonin was the first to propagate Nam-myoho-renge-kyo?")
Sentence 2:
"Other than Nichiren Daishonin, has anyone ever encountered the same persecutions, as were predicted in the Lotus Sutra?"
(There is nothing really wrong with using "besides" to introduce your subject [i.e., Nichiren Daishonin]. However, i would use "other than" at the beginning of the sentence, but i would use "besides" at the end or near the end of a sentence. So: "Has anyone ever encountered the same persecutions, as were predicted in the Lotus Sutra, besides Nichiren Daishonin?" Once again, this is a matter of personal style.)