Hey Peter. How I avoided the coastal batteries ? By not taking Prien's route but the south entrance and staying under water mixed with decks awash and immediately periscope depth or deeper, depending, as soon as someone shouted out escort in sight. I also rely on the UZO and Scope with TDC on to range enemies sighted. And under water my hydrophone guy is gold (it helps when XP points are allocated carefully) . The coastal batteries might have fired or it were depth charges I heard, but they were all nowhere near me. Sneak in, do your thing, sneak out.
And of course firing a torpedo at 11 clicks dead ahead to an anchored target is very doable. The Escort was a bit more tricky but the idiot decided to turn on his search lights about 3 or four clicks away making him an ideal target so I lit him up with two fish. Actually only needed one I later figured out.
About the planes. I chased off an Anson by directed fire and today two Hurricanes swept over my boat one pin pricking, Chased them off too. One hurri was attacking but I fired at him when he was quite near using solid lead angle fire so he broke off the attack and veered away and the other hurri followed him into the wild blue yonder. Probably lacked fuel for a prolonged attack seeing I was about 185 clicks out at sea from their base.
Always use Lead angle when firing at planes !!!
Also see my post in the main SH5 Forum part.
Ashikaga.