What is Apple's ios 10.3 APFS affect on iMac 5K Sierra iTunes backup?

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-Can my iMac (Fusion Drive) "mobile sync backup" FILES (device: iPhone 7Plus & iPad generation 4) be read for future recoveries, etc.?
-Can a copies of these files on my Seagate Drives (including one used for Time Machine) be read?
-Can my iPad generation 4 be updated to iOS 10.3?