I'm not sure doing this thru the JavaScript is the way to go but agree eVar expiry options need to be made more flexible. Ideally I'd like to see Adobe allow us to select multiple expiry options for each in the admin console.
Completely agree with all of the above... would also like to be able to alert on conversion percentages as these are often more stable. e.g. of those started an order, % that completed an order - alert if less than 50%.