1/ Yep. IIRC, that implies doing it the hard way given your FW version (i.e., a dirty unplug during an USBMS session).
2/ Yup. Or the legacy JB thread for whatever FW version you downgrade to, because it's likely to be vulnerable to a couple of different exploits.
3/ Unnecessary on a PW1, it's EoL, there won't be any significant FW update, ever.
4/ No idea how Overdrive works, not available over here

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