My DH and I have been on the Queen of the Mississippi 2 times. We are booked perhaps on the same cruise as you. America on 8/24/2019.
Most food is quite good. You will be given a menu card at breakfast to choose what you wish to eat for lunch and dinner on that day. You will have a choice of 1/2 entre if you wish to eat less (and not feel so guilty for having dessert). If you change your mind later or cannot remember it's not a problem, they are just wanting an estimate of how much of each item to prepare so as not to waste to much food. I try to remember to take my cell to breakfast and take a pic of our menu cards after filling them out. Lunch and dinner both have beer and wine offered and sometimes people request a mixed drink or after dinner liqueur. This is at no additional charge. There is an hour long happy hour just prior to dinner at which is no additional cost. If you want something that they do not have, they will probably have it after the next port.
They will have talks about the area you are visiting. There will be entertainment each evening, usually 1 - 4 people. Sometimes games in the afternoon with prizes (no additional charge).
There will be at least 1 tour in each port that is included and sometimes 1 or more that has an upcharge.