1. Yeah, I agree, with Chopper's sense of smell, you'd figure he'd be able to tell who the real Strawhats are, but consider this a)Maybe he lost their scent over the two years, or b) it's just a throwaway joke that we really don't need to read into too much. Oda often sacrifices logic for humor.
2. Zoro's part was definitely a callback to Mihawk's entrance, so yes, I think that was intentional. And I honestly just found the whole scene humorous, not mysterious. He just got on the wrong ship and had to fight his way out once he found out. Since when has he ever had a problem with cutting a few people down that are in his way?
3. Luffy probably didn't think they were worth the effort. If he can knock them out with haki why bother moving? Plus he's probably trying to keep a low profile.
4. I have no idea. Franky should switch to Coke Zero.
2. I guess I was thinking how Zoro could have said it in a Mihawk-ish voice, deep and a little reverberating. You're right. Ship in half, same thing as Mihawk.
4. Nah, Coke Zero don't have enough fizz to keep him going. I'm still waiting for those arms to be detached and/or fitting into part of the machinery/weapon on the Sunny. That would be awesome.