Have you ever been on a cruise?
What did you eat?
Are you allowed to carry on your own food?
Did you experience icebergs/perfect storms/Bermuda triangle/pirates and/or sharks?
1 and 2. Yes, with my family, through the Panama Canal in 1995. However, I was not a vegetarian yet, and I don't remember what I ate in any case. I've read that cruises have become much more veg*an-friend these days; I imagine that getting veg*an meals on board ship is much like getting veg*an meals at any restaurant, meaning, letting the chef know your dietary needs before you eat.
3. I don't know. I don't think we did in 1995, and even if it wasn't allowed then, it may be different now.
4. No, No, No, No and No. It took me about three days to get my sea legs, but it was a two-week cruise, so after that I was fine, and I had no seasickness or anything like that. My parents brought some Dramamine with them, but none of us needed it, not even when we sailed from the relatively calm Pacific to the much choppier Atlantic.
I think you should go on the cruise. If you're concerned about getting seasick, bring some Dramamine with you, and you'll be fine. And you'll have fun.