1. If eating in the main dining rooms without a reservation... sometimes you'll get in with no wait, sometimes 15 min wait. its a toss up.

2. You could book the wine lovers musical. This was fantastic! (oops...wrote this after seeing you don't want anything with a fee. this has a fee)

3. While on the ship you can pretty much make reservations for anything. All depends on how stringent you are on getting the times you want. You can head to guest services, look for the big computer screens located all over to book things or you can go on your room tv and book right from there. You can also call from your room phone.
The "big" shows run pretty much the same schedule as where as they comedy acts, game shows etc wont change too much per sailing. Check out some dallies from the escape... not too, too much changes sailing to sailing.