I've always wanted to start the One Piece anime but the number of episodes often discouraged me. I also agree that dubbed are waaaay to horrible to use maybe with the exception of code geass which I later got used to. An example is the Pain speech just before he destroyed Konoha in Naruto Shippuden, listening to him speak while the theme song played in the background gave me chills, but the dubbed version was just..... meh, cheesy to me.
After reading this, I just might reconsider my decision on the One Piece anime :-)
Try to binge as much as you can and do not go into the current arc before it finishes. Also keep in mind how many things end incomplete since they are just teasers for later arcs. Also be warned that Marineford is the peak of the show so far and nothing afterwards comes anywhere close to it.
I recommend the manga. I'm sure the majority of One Piece fans in the eastern part of the world would rather watch the show, but the pacing of the manga is so much better (FYI the manga's pacing is better compared to the anime although still not perfect).
You should. And you should start from the very beginning. The art and animation at those episodes are very 'meh'. But the story, the entertainment, the fun, the tear-jerking scenes it's all there. :)