1. Did "long time no see"
arrive in U.S. English from forms of pidgin English
spoken separately by both some Native Americans
and some Chinese immigrants?
The earliest recorded examples are from native Americans, but it's plausible it was used in other types of pidgin English at the same time.
2. When did this
turn of phrase first gain the recorded notice of an
American English-speaking author?
It has been recorded by American English-speaking writers in 1900. The author Raymond Chandler used it in a 1939 newspaper and 1940 book.
3. When did the phrase cross over into use by native U.S.
English speakers among themselves?
Chandler presumably helped popularise it with detective stories and film noir of the early forties.
The OED says it's a "Colloq. phr. (orig. U.S.) long time no see, a joc. imitation of broken English, used as a greeting
after prolonged separation."
Their earliest quotation is 1900 from a native American:
1900 W. F. Drannan Thirty-one Years on Plains
(1901) xxxvii. 515 When we rode up to him [sc.
an American Indian] he said: ‘Good mornin. Long
time no see you.’
Their next quotation of 1939 shows it was fully naturalised:
1939 R. Chandler in Sat. Evening Post 14 Oct. 72/4
Hi, Tony. Long time no see.
Their next is also from Chandler, in 1940's Farewell, my Lovely.
A good word for the random event (the party) leading to a positive outcome (she was there and said yes) is serendipity, though that doesn't describe your mutual friend, it describes the role he played.
Full Definition of SERENDIPITY
: the faculty or phenomenon of finding valuable or agreeable things not sought for; also : an instance of this
Examples of SERENDIPITY
They found each other by pure serendipity.
As they leapfrog from South Africa to Singapore in search of local
delicacies, the authors prove again and again that serendipity is the
traveler's strongest ally: many of their most memorable meals issue
from the hands of generous strangers … —Sarah Karnasiewicz, Saveur,
June/July 2008
Best Answer
Recent use of the phrase in African American English
The expression has been in use among African Americans for at least 28 years. Geneva Smitherman, Black Talk: Words and Phrases from the Hood to the Amen Corner (1994) offers this definition of the term:
A Google Books search finds a number of matches for "called me outa [or outta] my name." From Derek Bell, And We Are Not Saved: The Elusive Quest For Racial Justice (1987):
From Living Blues, issues 76–83 (1988) [snippet]:
From Gayl Jones, The Healing (1998):
The phrase appears in various other Google Books texts, as recently as Jazz Jordan, Lust & Hip Hop 3 (The Ms. Mogul Series) (2015):
Eighteenth-century use of the phrase in England
I was very surprised to find instances of "call me out of my name" from the 1700s, though these may or may not be direct ancestors of the term now used in African American slang. From Henry Fielding, Joseph Andrews (1742):
From The Batchelor: Or Speculations of Jeoffrey Wagstaffe, Esq. (1769):
From Dr. Last in His Chariot [a translation of Moliere's Maladie Imaginaire] (1792):
Conclusion
The instances from the 1700s are astonishingly similar to and consistent with the examples that occur in the 1980s and later, though I can't say with any certainty that the later instances represent a direct survival or revival of the older phrase. But if the modern phrase isn't a survival or revival of the older one, it is certainly the product of a striking coincidence in wording and usage.