It appears there's a lock on certain business categories. I tried changing a miscategorized listing from a retail category to 'Hotel & Motel' (the correct cat of the phone number and address) and the screen locks, preventing the form from being submitted.
Might be to keep travel affiliates from any shenanigans but it also prevents the corrected info from getting submitted.
As I understand it, this is still very much in beta. A friend of mine works on it. I think the reason the "add" isn't being shown is because they're still working on that part. Apparently, this was more of a hack from a few of the folks working there than a full blown product, but it's getting a lot of really good attention.
I also understand that there's some contractual thing about editing some of the listings. That's why the edit button isn't always there. They're also working that, but it involves lawyers so it's not going as fast as he'd like.