I think all you points are excellent and correct. However, I think that reenforces the realism that SHCE presents. Early radar did have a reduced range over the later models and there were cases when lookouts spotted aircraft before the early SD radars. In Germany, operations meant sending out the Uboats like a net, with Donitz in control of the whole show. Uboat Captains were constantly on the wireless to Germany, something that later on would prove to be a downfall. US Captains were basically given a patrol zone and set free to manage affairs as they saw fit. They did radio in contact reports on targets but only when they were forced to break contact or faced a superior force.
Japan didn't get into the convoy game until later in the war, and even then it wasn't as coordinated as the N. Atlantic convoys. Catching shipping along the shoreline was much more common in the Pacific theater than bluewater operations. There is much more shoal water in the Asian theater than in the N Atlantic. Especially around the Phillipines and Japanese islands.
Finding contacts you don't expect is SOP during a war. The enemy doesn't always play by the rules!
Christopher