Hullo-

This is , way, WAY to complicated & lengthly to get into here, but I'll try to address several of your points:

... it also postulated that New York was second only to Charleston as a centre for slave trading,

At one time in the mid-18th C- when NY & South Carolina were still British colonies both, this was indeed true.

and that the industrial base of NY was based on slave labour

Not true in either the 18th or 19th C.

I've picked up the notion that slavery was predominantly a Southern phenomena,

Yes, by the second quarter of the 19th. Century it was restricyed to the South. It had previously existed in ALL the North American colonies cum States.

so had it more or less died out in the North by the time of the civil war?

It didn't "die out", it was specifically legislated out of existence in the North.

For the rest, I'd suggest you investigate

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Harris, Leslie M.: In The Shadow of Slavery: African Americans in New York City 1626-1863. Chicahgo, IL, University of Chicago Press, 2003.

Gellman, David N. & Quigley, David: Jim Crow New York. NY & London, New York University Press, 2003

White, Shane: Stories of Freedom in Black New York. Cambridge, Harvard U. Press 2002

Berlin, Ira: Generations of Captivity : A History of African-American Slaves. Belknap Press, 2003

Berlin, Ira: Many Thousands Gone: The First Two Centuries of Slavery in North America . Cambvridge, Harnard U. Press, 2000

Berlin, Ira (ed): Remembering Slavery: African Americans Talk About Their Personal Experiences of Slavery and Emancipation. New Press, 2000.

Katz, William Loren: Eyewitness. Simon & Schuster 1995
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This list just barely scratches the surface- Enjoy!

Best, Greg