Irons of any kind are not allowed ( fire hazard). Irons are usually found in the laundry rooms for free. We were on a ship that had a fire in one of the cabins(scented candle) and while the crew performed excellently in putting it out in very short order, I would't want anyone to experience that.
you are not limited in your luggage amounts. Your carry-on must fit thru the security scanner(same as the one in the airport. Irons are a no-no. Fire hazzard, too many burned towels, furniture, counters, blankets, comforters and carpets. Travel Steamers are ok. Each passenger deck has a self-service laundry room with and iron & board.
Wrinkle reducer works good. Unpack and hang up your clothes as soon as you get them.