Allen is my ggggrandfather. I can give you his descendancy line, if you'd like, complete with sources. However, after researching for a few years, I have hit a dead end with George W. I have no idea who his parents are. I know that he was born in NY (1830 census) and died sometime around 1830 (he was listed in Whitehall NY that year's census). Legend has it he just disappeared, presumably dying near a mill in quicksand (undocumented). I very much want to find out more about his line, having documented Rosena back to the Huguenot Claude LeMaitre.
I can't answer your questions, as I've pursued them fruitlessly myself, but documentation for Rosena being the child of Benjamin Valatie Delamater and Anna Barnes can be found: The History of Harlem, James Riker, Chapter 24, p.520 (you can locate it online).