Lots of good thoughts in the above posts. Thanks for sharing your comments.
I have the hopper style basement windows. This afternoon I stopped by a glass shop and the folks there are going to cut a 4" hole through the glass for me. This will allow me to use the window location as desired and keep the hopper window closed, insulate the interior window surface as before (it's single pane construction) sans the vent opening, and connect to the booth vent without a problem. I also found a piece of soft yellow 4" thick foam in the shop (used it for isolating RC radio installation) that I will use for a vent plug along with a 4" vent cap as suggested above. This will take care of my needs. I am also adding a piece of new window screen fabric (also found in the shop) to the inside of the outside vent piece to help keep critters out. It all should work out fine. ?
Joe