2) Experience with ~1,000 units?
1% number could be accurate with regards to recent batches of autotuning 13.5Th machines, but initial batches (last summer, not autotuning) had up to 10% (or even a bit higher) board failure rate (within first couple of months) according to multiple sources, which was amply documented here and elsewhere.
Perhaps, most machines that you got were purchased during later part of 2016 or in 2017.
In summary, we have a better S9 in modification (from 12TH to 14TH) which have reducing the failure rate each batch, do we?
i have 3 machines from the earlier batches and i lost 5 boards from 9
1 of them sent for repair 2 times
2 of them sent for repair 3 times!
after repairing it and return it take from 1 to 3 months to stop hashing again
now i have one board on the way to then for the 4 time
and i have one with them it stopped after 3 days from repair and sent again under warranty to china ( the paid for shipping )
i have 6 autotune machine + 2 R4 and not lost a single board
i have room with digital control to make temp not exceeded 30C so temp on my room between 18 to 30C