When choosing a stateroom the best advice is to look at deck plans and take note of what is above, below, and beside your room. Is there a night club below you? Prob'ly gonna be loud late into the night. Are you below a busy pool deck? You'll prob'ly hear people moving around during the day. Also look at accessibility to elevators, stairs, etc.
My personal non-concierge level favorite (I've cruised on Disney's newer ships 5x all in various verandah staterooms in various locations) would be the 04E staterooms. I enjoyed the bigger verandah, quiet and convenient location. Another consideration, if you want to look out over the guest areas while docked at Castaway Cay you'll want to select a room on the starboard side of the ship.
Aside from the upcharge fine dining venues and some of the upcharge snack options near the theaters & via room service, the Cove Cafe specialty coffees, or bar drinks food & drinks are available to you at no additional charge 24 hrs a day. You have to let go of the parks mindset.
Breakfast & lunch will have 1 of the table service venues open as well as the buffet. Throughout the day the walk-up counter-service places are open. Dinner you'll have your assigned main dining room. The buffet venue will be an option on your 2nd night only. (It's not open the first or last night of any sailing so on a 3-night cruise night 2 is the only one available.) The walk-up windows will have food until like 11:00 or midnight. Room service is 24 hrs. It doesn't have the most extensive of options but it's good. We love the BLTs and fries.
Also, if you order room service it's nice to tip whoever brings you the food a couple dollars depending on how much you ordered. We keep an envelope of $1 bills for this purpose. Believe me, on the cruise you will not have to go far or look hard for food at any given time.
If you're driving from Chicago to WDW you can easily drive yourself on out to the port. There's like $5 in tolls each way between WDW & the port. It's not a difficult drive at all. Very easy to navigate. You can park right at the cruise terminal for convenience. Parking for a 3-night cruise will cost you $60 in Disney's structure. To me, it's worth the extra cost for the convenience. Check out
this page for driving instructions & info. Then when your cruise is over you can drive yourself right back to WDW & park at your resort there for the next 2 weeks.
Good luck and happy sailing!