I wouldn't plan on eating at any table service restaurant without an ADR. The dining plan means everybody is trying to get in. Make 'em early and be ready.
I agree. My DSister and BIL went in the "quiet" of January, and could hardly get into anything. I had warned them to make ADRs, but they didn't listen Restaurants were giving them 3 hours+ for seating, and often they couldn't get anything at all if they walked up 3 hours before park closing. They ate off property and at DTD most of the time.
Also, I don't know when you are going, but you probably want to call ASAP. With free dining coming up, you will have an even harder time getting in. Good luck!