I am familar with friction shifters and I know that you can use them even on Campy 10 speeds, heck most likely on their 11 speed systems too. With friction shifters you can move the deraileurs any where you want them since there is no detent [index] to lock them in place. The main difference about the friction shifters is the diameter of the bottom of the lever where the cable rides. The larger the diameter the more length the cable is pulled. Usually the small diameter can run 7 and less but my understanding is that the 8 or higher needs to have the larger diameter version. I used an 8 speed friction set up for my Record 10 speed tandem but I changed it to a 10 speed down tube [a converted 10 speed bar end used for TT bars] because I could not hear the misalignment due to the larger distance of the tandem. I eventually changed to brifters but more because of the way the additional tubes were in the way of shifting [could not use one hand to shift both levers]. The left lever does not make a difference since the front deraileurs all pull about the same amount of cable to make them work. That is all that there is to know about the friction type.
Index should be schooled by someone who know what they are talking about so that is where I will step a side.