No, they do not serve Dim Sum.

No

No, 1. they don't serve any sushi. 2. they don't serve any food in "all-you-can-eat" buffet style. They serve Chinese food "à la carte" from their the menu or they will make you off menu items if they have the ingredients.

Sorry, nowhere on the internet has their menu. You just have to go there. Definitely try their "real" chinese menu.

There is a menu on the internet but the prices are old.

It's probably because they had bad experiences