Washing it yourself is totally fine after PPF, just stick to soft microfiber and proper car shampoo rather than anything abrasive or high pressure directly on edges. Mine's been easy to maintain on weekends, no different from washing a normal painted surface really.
45 degree heat combined with stop and go traffic is genuinely one of the worst conditions for S tronic fluid viscosity. If the fluid has never been changed on a 2016 A6 it is almost certainly overdue and worth starting there before assuming anything more serious.
Following this, we're facing a similar standardization decision for our facility. Automated picking consistency is our main worry too, curious if anyone's had actual geometry drift causing picking errors.