An i7 is definitely a better processor, especially for heavily threaded applications like editing. For the average gamer I don't think there is enough benefit to justify the increase in price.
As far as longevity is concerned, there may be a little increase with an i7, but historically there isn't much. The improvements in IPC with newer processors tend to outweigh the additional threads when you start talking about 7+ years down the road.
Stock cooler vs aftermarket doesn't make too much of a difference if you aren't overclocking. They definitely will help the processor run cooler, but really most modern Intel chips don't get beyond 55 or 60c at stock clocks, which isn't bad at all (I use a stock cooler). Aftermarket coolers can definitely be a little quieter, which is nice. And they also look cooler, if that's your thing.
If this was my build and money, I'd stick to the $1500 price point and the i5, much more bang for the buck at that price. You can spend the extra money on a nicer monitor. Aftermarket cooler is optional, I kept my stock to save a few bucks and out of laziness (some coolers are a royal pain to install).