Newbie questions....

[quickening58]

I think these are educational questions....

In patroling Rabaul area, early Nov43, Allied Air is obviously doing some airstrikes. I notice sunk ship icons on the beaches, and even inshore (up in the trees) in areas. Are these icons for other than ships sunk? Aircraft losses?

Occasionally "survivor" icons show up in airstrike areas. Have assumed they are downed aircrews and usually race to the area,when possible (often an hour or more run) but never find anyone. One time had 3 survivors within 3 mile circle. Was frustrating plotting out searches and never finding any of them, along with the icon disappearing Am I missing something?

I need some confirmation on range circles and arcs, mostly of the escorts.
Full circle are theoretical visual range of watchkeepers? In this image, there are two full circles....? Early primitive radar for one of them? Am assuming the longer range arcs are sonar (active?passive?) but can't put a finger on the short range arc.

Any help with this stuff would be great