Let me address the 2nd part of your post:
The CO (Carbon monoxide - not CO2 - carbon dioxide) risk is for a car in an enclosed area (like your garage.) Modern cars have better ventilation systems -- I think almost all will have a fan running to change air in the cabin at all times, so idling for extended periods is not as risky as it used to be, but an open window is always a good idea in those situations. But I have to caution that a window may not help if you have a faulty exhaust system.......I owned a Prius for 8 years before this van and I left it running multiple times in the first year. It was so quiet and if I was distracted it was easy to do. Not sure about the risk of that...it never seemed to run FULL ON for long so maybe the CO2 thing wasn't an issue??