Yes, you need an ADR. It's a combo of QS/table service. Also once you get that ADR, choose your food before it (you'll get a message usually) so you can go in the short already chose food line instead of the long still need to decide what you want to eat line.
They weren't taking lunch walk ups at all when I went in March 2016, early May 2016 or mid-September 2016 or early December 2015 - thankfully I had my lunch ADR made on the 2 times I wanted to eat there on those trips. I heard people being turned away while I was checking in. The other 2 were spur of the moment, I'll just try and see if I can get in and it was a no. All times were after 1pm.
