All American ships add 15% to bar bills and add gratuities to your onboard account unless you opt out. It might be easier to pay the standard gratuity so that you don't have to worry about extras. Your normal holiday day wear is perfectly acceptable onboard and ashore and a lounge suit for the gentleman and cocktal dress or long skirt and sparkly top for the lady will serve for any formal nights. Some gentlemen do wear dinner suits, but it is not essential. You will get a daily bulletin delivered to your cabin each evening explaining what is happening the next day. I'm sure if you ask for this in a large print format they should be able to help. The crew are there to make your hoiday the best they can, so talk to them and ask for anything you need with a smile and you'll have the best holiday ever.