MailStream Plus-How To Find instructions documented about setting up a Drop Ship mailing, such as to SCF or NDC or ADC entry points?

Yes, the MailStream Plus Open System User Guide, in Chapter 4.  Or for the IBMi (iSeries, AS400) platform, in the MailStream Plus IBMi User Guide, in chapter 10.

Although the discussion is about SCFs, the same information generally applies to NDC/ASF and ADC entry points when using them, such as with NDC PT or ADC PT parameters.

Note: In both documents, following the discussion/example about doing an SCF drop ship mailing, there are instructions about using DRPKEY to tell MailStream Plus (MSP) the Locale Key to use for USPS facilities.  
Normally DRPKEY(s) should not be used unless needed, such as when/if MSP is unable to look up the entry facility's Locale Key.  But normally MSP can look them up and that is preferred to manually entering them, because the USPS does change facility's Locale Keys occasionally.
UPDATED:  April 14, 2017