Pedro's story? : D Could be, dunno.
That is very true. Even Big Mom, that power-hungry heartless killing machine, got a sad back story, that was kinda ridiculous : D I guess it is just hard to write a back story that isn't a sad one. Like, how do you make a good flashback for Big Mom without making her a victim?.. unless you do something very clever it would end up being way too linear and simple.
Take Doflamingo's story. It is pretty great, but it only works because he had suffered enough to justify his attachment to his crew and his hate for the rest of the world. Also, I've been reading the initial volumes of One Piece, and my favorite character backstories are Usopp's and Nami's. It is easy with Nami, her story being so tragic and reflecting in her personality in all sorts of ways, it is a generally well done sad story. But with Usopp, there is nothing tragic about it, it is just a nice story. I really liked it though. I am talking about him being the village's liar, and him trying to entertain that sick girl with his lies.
I know what you mean =) Though there is like 99% chance we will get to see more of Zoro's past. Right now it is weird and incomplete, especially the story with Kuina.
That is not a big deal really. The results of any fight are clean to see, so at worst you'll miss the exact sequence of actions that lead to it, and even that would be a rarity.
Reverie is so tiny, it wouldn't make any difference. But it is also an infodump, so beware : D I am sure it wouldn't be a problem for you either way, pick whichever arc you want to start with. For me the real fun comes when you read the current chapter and can see how the community reacts ^^ And OP is much more suited for weekly readings then for marathons, Oda writes it that way.