Regarding Funky Dealer from JSRF's lead vocals, I messaged Hideki Naganuma himself on Twitter hoping that he remembered where it was from, however it turns out all the sample were off his HDD and he didn't grasp every CD's name.
Afterwards, I decided to message the composer of another song that used the same sample-- Nobuyoshi Sano, who composed "boots" for Zuki-in 1995 Winter.
https://twitter.com/sanodg/status/427249164812963841
He says it's from Sound Ideas' series 3000 sample library. Could anyone verify if this is true or not? It's a good push in a direction, but still...