There's no need to buy hddfancontrol - ssd fan control is free/donationware and works a treat using the S.M.A.R.T. data from the SSD. I've used it on mine and many other iMacs, download from here: http://exirion.net/ssdfanctrl/
You'll also need a caddy to convert the SSD to 3.5" - the basic little tray that for instance Crucial sell is not good enough and leaves the SSD hanging on one screw. Buy something like this one: http://www.amazon.co.uk/dp/B00F3QFKNS