ummm, the best thing to wear on a cruise is something COMFORTABLE..not sure what exactly you are planning but a corset?? You will go thru an metal detector much like at the airport..so yes, belts, keys, anything metal all must be removed. Do yourself a favor...just dress normally. At the very least avoid the whole corset thing.
There will be a lot of waiting around, then when you board, it will be rather crowded- especially at the buffet. Your cabin won't be ready until around 1.30ish so you might want to wear something comfortable. Maybe pack your swimsuit in your carry on to enjoy the pool a bit?
Why do you want to draw attention to yourselves like that? Just curious.