Welcome to cruise-chat. You really need to sit down and talk with a cruise oriented Travel Agent. They will ask you questions to better qualify you which cruise line fits your life style.
Based on what you've said here though it does sound like NCL or Carnival would be a good fit for you. NCL is Freestyle for dinner and dress which sounds like it meets your needs.
All cruise lines have added expenses. Gratuities, drinks & coke, shore excursions, spa treatments, gift shops, bingo, photos, to name a few. All cruse lines have pros and cons. This is why it would benefit you to talk with a Travel Agent.