Venting the range hood has been kicking my butt. The outside wall opposite the range is the housing for the tankless water heater, and the wall is full of supply and drain pipes, gas lines, and wires. I found a path I can snake this 4" flex duct around though and the vent itself is now hiddwn on the back side of the water heater enclosure, high enough that exhaust won't go back in through the kitchen window.
This is the scariest drill bit EVER! I needed to drill through the kitchen wall in just the right spot to run the exhaust duct. The hole saw bit I needed was $60 plus $20 for the extension. For one hole. Byron suggested Harbor Freight and I found this adjustable one for $7. It worked, but after drilling through the cement siding board it's all worn out.