I had never heard of "fly" as an adjective before.
I'm confident you're going to start noticing this use of
fly as an adjective from now on.
However, it would certainly be interesting to hear a deeper analysis of the whole rap part starting at 2:30 from you as a music and language expert. To me personally, it's somehow enigmatic that a multi-millionaire is musing so much about his finances, given the fact that even if -for whatever reasons- he went bankrupt tomorrow, he just needed to make a new album or go on tour to be become a rich man again very fast. I mean that would be super-easy for him, wouldn't it? If I were in his position as a famous celebrity, money would probably be the very last thing I'd worry about. But maybe I just got the lyrics wrong and you can bring light to the mystery?
Well, the first thing I'd remind you of is the fact that in any kind of writing, including rap, the 'voice' is not necessarily identical to the author. That is, there's no reason to automatically assume that Nas is singing as himself. However, it does seem to be the case here, and so I understand what you're saying. I'm not a fan of Nas's rhymes and I don't really know much about his personal life, so I can't really offer anything illuminating as to what he might be trying to say.
To be honest, apart from the obvious
Like smoke, girls lean round a player, I can't see much of a link at all between Amy's part and Nas's additional verses. I'm not even sure how much Nas himself was thinking about any kind of link.
Apparently, Nas penned his verses after Amy was already dead, so she definitely had no part in what he's going on about. For a bit of context, see this link to Songfacts.com:
https://www.songfacts.com/facts/amy-winehouse/like-smoke
