Q: Is a development kit available for the PN7150X?
Yes, the OM27150ARD with Arduino compatible header can be ordered via AVNET
Q: Are general design guidelines, data sheets and app notes available to me prior to approval of specific Apple controlled PN7150X documents?
Yes, all of the standard design principals used in the generic PN7150, also apply to the custom PN7150X. The PN7150X includes additional content but is form, fit and functionally identical to the PN7150