top to bottom:
1. No two computers are alike, and no two runs of the game on the same computer are alike. You never know when the game or machine wants to take a holiday... The main things with weather are not doing high TC when you do hit a storm, since the TC seems to interfere with the chance of a roll. It can be tough to notice when you hit a storm though, but watch for the boat's speed to fluctuate, along with rudder changes if you have set a course. Slow down to 512x max. Also, there can be times where you go from storm to clear and back to storm, and do not notice due to TC use. Shelling out to windows will also do that, since each time you go out, the game's "clock", which is based on a DirectX v9 dll library call, gets re-set. But "weather" is not realistic in SH4. I would rather be in a storm with somewhat limited visibility, than the dead-calm you can get stuck in just as badly. It can be near-suicide to attack when it's calm.
2. In a regular FotRSU activation, you are dealing with the Stock game's "Dud" rate. So you do have to have the choice enabled on the Career Captain's Office "Options" "Game Play" menu to encounter duds. Also, in the AddInModzPak are several choices of dud rate modifiers. The "650_MoreDudz" is probably the closest to "real life" percentages, and most of the torpedoes do have issues, including the Mark 10 running 5' deep. It amazes me that BuOrd would not have taken the weight of a real warhead, as compared to a practice head, into consideration when they did their settings "recommendations" ("Do this or else").
3. The Mark 23 at first costs renown, but when the "fix" is in, it represents the "repaired" Mark 14 and becomes free. But there are still deep runners, duds, and circle runner chances. Just not as high. You'll also notice that CapnScurvy has the warhead default from a magnetic pistol to impact pistol about then.
4. Yes Martha, we have no bananas, and the Japanese subs that carried planes do "launch" (spawn) airplanes. They will do it based upon your sub's detection. In other words, if a shore battery, a ship, a picket, a plane etc., happens to see you, and the sub is close enough, it will spawn a plane that will come your direction, with a pre-calculate angle error, similar to what the guns have. If it's time for their radar to be active, they will bee-line for you and attempt to put the whoop on you. Didja hear it "screaming" as it came in? Some of the planes have that now. Sounds like a Stuka, 'cause it is that sound (thanks Jeff!!!)
5. Blackadder is required study on this team... as well as a few other shows... lol - must have the proper "chip chip cheerio and all that!"
PS: If I missed something, berate me. "sorry" ahead of time!