I don’t know that you need an intake, if you’re exhausting air should come back in passively. Houses aren’t really air tight so air should flow. If you’re exhausting more than 500 CFM you might want to look at a make up air unit to return air at normal temps, especially in cold climate or you can chain furnaces.
Not sure you need the CO2, back when I did wine you can get it to about 12% before the yeast dies. Cheap way might be to ferment some molasses and make some rum after it’s done burping, have to run it through a still to get higher % alcohol.