In regards to the first question, well...US nucs were often able to use the periscope for underwater "hull shots" on Soviet vessels, so it's possible. However, the optics were considerably more advanced, and it probably depends on the water conditions.
...not much help, am I?
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Vanvikan, Feb. 2009: ordinary human, KIA, night 4
HMS Thanatus, May 2009: ??? human, KIA, night 7