Choosing processor for MacBook PRO Retina
Generally amount of monitors connected does not have that much influence on cpu performance. Also, i7 CPUs shine most where tasks are prepared to use multiple CPUs/cores (code compiling, audio, video, graphics editing, rendering). Thus I don't think you should consider CPU update because of amount of monitors you want to connect.

For normal usage andeven gaming I'd just choose the best i5 you can get and get better SSD or more ram instead.

As for the cables - you will have 2 TB ports and HDMI - if you want to leave one TB free maybe use those? So, if any of the mentionend monitors has Display Port (DP) you would need 1 mini DP/DP and one HDMIcable.

I think you can also get TB hub, that will allow you to use one TB to connect both screens, but I haven't tested it.