I agree there are many “common” occurrences of name-and-form, i.e., used in a Brahmanistic manner possibly for a Brahmanistic audience. I suggest the following links for context.
I recall @Sujato suggested a corruption in SN 47.42. Since the words samudayañca atthaṅgamañca are generally used for the arising & cessation of dukkha, it seems strange they are used for the arising & cessation of the Satipatthana. Even @Thanissaro required to use multiple footnotes to explain this very short sutta. It seems SN 47.42 may be a later addition or corruption despite its final verse seeming to be a favourite for adherents of mind-only Solipsism.
What is meant by “external” name-form? How can “name” be “external”? 
How can “name” cause contact? Surely contact with an object occurs before the object is named?
What does the word “descent” mean?
DN 15 seems to define nama-rupa differently to SN 12.15. The DN 15 definition seems to be a pure Upanishadic definition. DN 15 says: “Suppose there were none of the features, attributes, signs, and details by which the category of physical phenomena is found… Suppose there were none of the features, attributes, signs, and details by which the categories of mental or physical phenomena are found. Would either linguistic contact or impingement contact still be found?.. Suppose there were none of the features, attributes, signs, and details by which name and form are found.”
If the above is namarupa, how can this namarupa “descend into a womb” and what is the connection of this “descend into a womb” with the following connected phrase: “there is a pathway for designation, to this extent that there is a pathway for language, to this extent that there is a pathway for description, to this extent that there is a sphere for wisdom, to this extent that the round turns for describing this state of being, that is, when there is mentality-materiality together with consciousness”.
A wall suttas for me, rather than valuable gold or tasty KFC nuggets. 