Just zoro

In the dedication yes, but luffy has more determination. If that makes sense.

Zoro = Vegeta
Which is weird seeing as he's voiced by Piccolo.

The ladder on the right seems to lead to an even larger hatch, judging by the width of the ladder. My guess is that they brought it down, not up.

Yes, but zorro is usually in that deck on the very top of the boat so there's only the roof on the top.

It's like how they get huge furniture into houses, you remove the windows.