Xandir is supposed to be Link from The Legend of Zelda video game series. Foxxy is supposed to be a sassy 70s cartoon a la Josie and the Pussycats. Ling Ling is supposed to be a Pokemon. As for Spanky Ham, you’re on your own with that one.
Pretty much sums up my guesses. Wooldoor would be closer to a Spongebob than a Stimpy. Xandir reminds me of Link from Legend of Zelda, but probably draws from any of those RPG games (Final Fantasy, Phantasy Star, etc.). Foxxy seems an obvious nod to Josie and the Pussycats. Ling Ling is without a doubt a rip on Pokemon’s Pikachu.
Don’t ask me how I’m so sure about this, I just am.
Despite what the anonymous IMDb contributor said, Spanky Ham is not supposed to be Porky Pig. He is supposed to be your standard, foul-mouthed Internet Flash cartoon character. As for the rest, you seem to be on the right track, but most of the humor comes from the fact that the characters are either exaggerations of their origins (Ling-Ling has many stereotypical Asian traits, Foxxy Love has many stereotypical black traits, etc.) or are the exact opposite of their would-be character traits (Captain Hero is a sissy, Clara is a racist, etc.)