Is the interior surface smooth or ill regular?
What you were looking at in the picture is on the inside of the glass and also on the outside of the glass so I guess the answer to your question is yes it is got an irregular feel to it. But I will say it is incredibly beefy

Holds how many ounces?
A single whiskey glass can hold up to 9.5 fl oz. 

Do the glasses actually spin? Or is the video just rotating to show the mountains?
the glasses do not spin. They're just regular glasses. They are nice heavy weight. They are very nice design with the mountains on the inside.

Will a 2.5 ice ball sit inside the glass?

What are the dimensions across and high?
3 1/2 inches diameter and 3 1/4 height