The Scythe Mugen 3 is definitely too overkill for this setup. And its size makes it inappropriate for a system like yours. A Scythe Samurai ZZ or Katana 3/4 will easily
be able to cool the CPU at 300-400 rpm (i.e. silently). Just have a look at the SPCR reviews. For example, the Samurai ZZ can easily cope with a 95W quad-core CPU with the fan at 11 dBA/1m. And you're not going to stress your CPU much with your usage.
Even an Arctic Cooling Alpine 64 would be able to cool your CPU silently. (my Alpine 64 Pro cools my triple-core Athlon II at 500-700 rpm. Not audible, and I use it for gaming which is more demanding than your usage).
It is impossible for regular users to feel the difference between SSD's. They perform virtually the same. So whether the SSD is overkill or not depends on the price. Just pick a reliable SSD and you'll be fine (the Samsung is a reliable one btw
And no, overclocking your RAM wouldn't make much sense.