As such, I want to know what is the Canon "equivalent" of the Nikon D700. I know that there will definitely be problems in comparison. I know that the 5D2 doesn't really match up to the D700 in terms of specifications like AF points, FPS, etc.
no real direct comparison; 5d3 for speed and AF, 5d classic for resolution
Also, is the EF 50mm f1.4 as good as the AF-D 50mm f1.4 in terms of accurate focusing (I know this varies with different lenses), speed of focus, colour rendition etc? Individual lens reviews can only say so much so I hope to know if they are comparable.
both of those 50mm f/1.4 lenses are quite good, color rendition is subjective and editable so a moot point to me.
I prefer the Canon one for slightly better border and corner performance, tho on the lower rez D700 the Nikon lens' slightly reduced performance is not likely even noticed. On a D800 the extra sensor rez could allow an even greater effective overall system resolution.
On a good Nikon body, like the D700, AF speed of the Nikon's screw-drive lens could be a little faster than the USM Canon lens. Nikon's AF accuracy is also very good, altho I've not used the D700 myself. Those who do shoot with the D700 love it for various reasons and the AF is one of them.
Nikon's D-series lenses are reputed to be very fast focusing when used with high end bodies.