They are sold as left or right... don't know what it would do if putting on wrong side... though just the GT350 left shaft is a few dollars less than the S650 right shaft... and the full set of the GT350 ones can often be had for even less.
I don't know if I can speak for the efficiency (that would take some complex instruments)... it does seem to keep the AITs cooler. Running the FP tune. Price is pretty high, but there isn't really any other choice... unless you want to start cutting things up to fit the race intercooler.
I'm running the Mishimoto intercooler... got the charge pipes as well. I believe that the two you listed are the only ones currently available. I would not hold my breath for eurocompulsion... they said they were working on one two years ago when I contacted them.
Whatever tire is installed on the REAR from the factory, is the tire size programmed into the computer...(GT 27", PP or DH 27.7", DH HP 26.5") the fronts have nothing to do with it.. square/staggered also has nothing to do with it. If you replace the REAR tire with something less than a 3%...
Same size front and rear are not required... DH and GT PP cars have 27" front and rear is 27.7.
Edit: biggest thing is to have the correct rear tire size in the computer.
With the current oil monitor, you could change your oil today and park it for a year... it will tell you to change the oil when starting it up a year later.