I bought/downloaded Wire Tap from http://www.ambrosiasw.com/utilities/wiretap/ back in 2013 for about $50. I don't think it's supported on newer Mac OS like Yosemite any more but there are other similar apps out there – I might have to consider these if I upgrade the OS on my iMac.
1tb hard drive. 2.9 ghz 16 gb of ram required. It had 8 but I figured as I’m in there......
Got a screen adhesive strip kit incoming. Lots of fitting guides. It’s a late 2012. Not decided where to get ram yet.
You've got a whopping HD with enough fast grunt too.
Crucial Memory is fairly good – we've got chips from them at work http://uk.crucial.com/gbr/en/memory-info just enter your make/model/year/screen size and the recommended RAM will pop up. You can find the exact specs from "about this Mac" by clicking the Apple symbol in the top left corner of the screen.
2 x 8gb incoming and screen adhesive strip kit. Total £135. £128 returnable if I screw it up. Just had a chat with a very hepful friendly guy at the supplier.