No, I wont be overclocking, hence the 2500 rather than the k version.
Than don't get a cpu cooler you fool!
No need for anything else than stock cooler unless you overclock it up to 3.9ghz or higher.
About crossfire/sli, I agree, lots of games have problems running in those modes, sometimes you wont even benefit at all.
Edit: putting it together is very easy, it's not like playing an instrument at all. It's all just plug it in and go have fun. Just watch some vid on how to do so and it'll be easy.