Usage of 何 in Buddhist Hybrid Chinese
"以何" was used in classical chinese roughly as "by (以) which / what (何)".

eg 禮記﹒問喪


  或問曰﹒杖者﹒以何為也


三國志﹒董昭傳


  問﹒禦以何術


though, it's not 100%, most of this usages were questions.

the verses "以何方便　而受道法　何因令獲　從佛經教" is from 正法華經　卷第七

http://tripitaka.cbeta.org/mobile/index.php?index=T09n0263_007

in which 方便 is upāya-mukha (方便門), since there're many ways to learn buddhism, "以何方便" in this context means by (以) which [one] (何)  of the ways (方便).

about the question mark, it depends on the version of translation. here's one that text are punctuated with dot only.