Ok, a 'Vessel that you can actually walk on' sounds cool af but I do feel that such a large vessel would need larger bodies of water to really make it have maximum coolness. Could also be like a tower or castle you could walk on the roof of? Ranged combat viable in base defense?
I have doubts about free form building though, because currently you get an idea how powerful village, group or person is by the structures there. You see an tower or a long hall and go 'danm, look at them!' I also suspect that free form building would be cheesed to hell. That and in general the ability to look at something and know what is its I feel is important here? IDK maybe I'm just being afraid of change but I don't think I'm too keen on the idea.
Combat I cannot weigh in effectively. I think current combat is alright but this is the first world I've done combat so I've no other point of reference. I can say though that as lower stats I had to switch combat decks that favored different colors but now I've found that a very basic green deck can kill most medium to small game with minimal HHP loss if any.
Dungeons should not give any finished products imo. Resources, natural curios, things like that. No tools, no armor, nothing that under mines 'players create everything' that is the single more unique thing about this game is that every house, tool, clothing and piece of furniture were made from players from wilderness.