In the C34 the red and green are the side aerials, should be same, I got best results from combining one side with one rear. so red+grey and green+black eg. Black should just be another aerial plug.
2nd photo is fine, just unplug it or cut it and put your own plug onto it, and this then goes to relay. 2 wires for the 2 amps.
Don't think it matters where the grey plugs go, otherwise Nissan would have made them different, just make sure everything is working before you seal it all up.
Any standard 4 pin normally open SPST relay from an Auto shop, 30 or 40 amp. If you are really stuck let me know and I can send you one. Bosch/hella or narva etc
Cig lighter is ok for RED ACC wire + power for the amps.
Yellow needs to connect to always on 12V, Should be a source there somewhere, I think I used the CD stacker wire harness in the C34. Dont connect red and yellow together, you will lose settings everytime you switch it off.