1. You can run windows 10 FOR FREE, you just won't be able to personalize your system. Once you have the money, buy a copy of windows 10. (I have done this personally, I am a computer consultant, and I have ran windows 10 without a product key for long periods of time. Again, all your locked out of is personalizing your system, so all the core functions perform fine.)
2. The wraith cooler on the 2600 should do fine, but in the future i'd recommend getting a CPU cooler especially if you want to overclock.