I think they do it 11-2 m-f. But they open at 11.

You can find many of your questions answered on their facebook page. I found their food to be well prepared. Buffet is a lunch/afternoon thing.

I'm not sure. They renovated and built a bar area where the private banquet area used to be.

No evening buffet.

I don't think Longhorn monitors this string in real time. I suggest you call them :-)

Yes