Get the dish. Get it from a local dealer, and keep your receipt. Mount it on a piece of plywood or something sturdier so you can aim it and have it hold position well. On a nice day, aim it with the window open. Make a note of the best signal level you get thru the open window. Then shut the window. Make a note of the new signal level if it changed any.

If it drops off too much with your window closed, then open the window again and try placing a piece of plexiglass between the receiver and the dish. Make a note of the new signal level. If the plex seem to work, then simply "paint" ribs on it to match the previous window glass. Be sure not to use lead based paint.

Done? You'll have all the information you'll need to answer all your own questions. See, isn't that easy?

Dave