I would add that the passenger side collects enough oil to need draining every now and then, but the driver side doesn't seem to have ever collected even a single drop.
The driver side is not necessary, but it won't hurt anything if you install one. I put a driver side separator on mine just for looks: it fills in the open space on that side and it matches the beautiful passenger side separator.
I could be wrong, but I think I read that air-oil separators don't need to comply with CARB (California Air Resources Board) rules. Breathers, on the other hand, that vent to the atmosphere, are not allowed.
I have the GT350 version of the Bob's Autosport separators, but not mounted to the firewall. (They are mounted near the struts.) I got both passenger and driver side separators because I like their looks, but you don't need one on the driver side.
They are sealed units with a valve at the...
Tech is leading automotive evolution right now. Maintenance of tech should not be an issue. Besides, the way things are now, tech is not maintained, it is replaced by upgrades.
I can't answer most of your questions, but, last things first, if your car was built before Sept. 1, 2016, I think you're in the group recalled for the oil line issue. That doesn't mean you've got a problem now, but the recall should prevent the problem from ever occurring. Even if your dealer...
It will usually help to update the tune anytime changes are made to some engine aspect.
Even a bone stock car can be put on a dynamometer so the various parameters of the tune can be adjusted to fit the engine's particulars -- a "dyno-tune." A dyno-tune will get the most out of your particular...