Dear it is just regular maintenamce . People use 0w-20 or 5w-30 in Turbo and same in Oreil. Not much price difference.
Plugs have life of 100,000 km for Turbo also. Very few eople have experienced premature failures which was due to bad fuel in 2016 . But this was resolved once fuel quality is improved and software update which removed knocking. I haven't changed my original plugs and it is 30k driven.
Steering rack is a problem which can occur anytime. Yes Honda accepts it as Quality defect and replace it . If car has full service history , it would be replaced by Honda even after out of warranty.
The car you sre looking for seems good and well maintained. I would advise you to buy it and you won't regret it.
BTW you can run on regular petrol without any issue whatsoever. Mostly you will find wrong infirmation/opinion from the persons who don't own Turbo
Best of luck and Happy driving Turbo