Brook is Saul Hudson aka Slash ( gunsguns n roses ) he. He is a musician and one of the best known guitarist in the world these days. BrookBrook's personality doesn't make sense at all as he is a pervert, which may have good manners at times but acts silly. heHe also looks gay, which reminds me more of Micheal Jackson that would be the best fit in regards to his personality in the manga, but MJ doesntdoesn't have an Afro hair stylehairstyle as a trademark where as, whereas Slash does. howeverHowever, if you look closely inat the poster of the 'guns n roses' album 'Apetite'Appetite for Destruction' you will see brookBrook with the skull face wearing the shades and hat like slashSlash does.
I will speculate frankyFranky more as Arnold Schwarzenegger for he is a cyborg related to 'The Terminator' and he always wearwears underwear posing like a body builder. Arnold was a body builder and had won many titlestitles; if you looksearch on googleGoogle for some pictures of this guy you will see him posing with underwear. thereThere are surely more clues onwith regard to that matter like his real name 'cutty flam''Cutty Flam' and the star tatootattoo that he has on his elbows.
Darn i
Darn, I almost see Duke Nukem in him.
Zorro , the name says it all. Aka Sero, Don Diego de la Vega, he always wearwears his bandana when he fights seriously which makes it lookshim look like a pirate, but it also covercovers his eyes making ithim look like Sero when he is not wearing his hat. whenWhen it comes to sword play, he useuses one sword-sword style which is unmatched because of his dexterity. itIt is like fighting someone using 3 swords and the 'Z' of his trade marktrademark makes it of 3 slashes. theyThey say Sero is a fox with three tails related to zorro santoryuZorro Santoryu.
for usoppFor Usopp and chopperChopper you are correct , iI am curious to know about the rest. Remember one pieceOne Piece is supposed to be funny, this is why the personality differs from the real protagonist, but when they are serious intoin a fight it turns them tointo the real thing.