Should I use a eight or nine inch round cake too support the weight of a pint of liquor on top of the cake? And should I place the dowels around the circumference of the bottle?

I guess it depends upon the size of the bottle.  Try laying it on the cake pans to see which one looks better.  I would definitely use dowels to support the bottle.

and the cake is not necessarily gonna support the bottle -- go on you tube for instructions on how to add a board and yes do the dowels within the circumference of the bottle under the board -- you can ice the board to hide it or put flowers and scrolls on it or whatever --