Hmmm...
1. What's wrong with the current one? While not the absolute friendliest, SHIII's editor is quite easy to work with. I've never had to take longer than a few minutes to put together just 'a quick mission'.
2. I can do it in my head too, but I love SHIII's graphics and by no means should this relatively successful new feature taken out, I think. There's few complaints about them, simple as that, and I think what you speak of as "irrelevant detail" is actually crucial immersion that drew a lot of new players into this game.
3. It'd be nice, but not absolutely essential. More generally, though, I agree that some special missions should be re-introduced into campaign.
4. Would be nice, but I'd say that's a comparatively bland task. I'm personally fine with the focus on attack boats. Perhaps as bonus, but not a 'must have'.
5. It's kind of in SHIII already. It's limited by default, though modders have definitely extended this. Frankly, I'd rather their campaign in the open sea be more complete than have this far more exotic role for submarines done.
6. ...it's in SHIII
7. Again - I'd rather only have the essential America, but done RIGHT - but this would be a nice-to-have feature.
8. Agreed. Some of the finer systems control in general in SHIII was sorely lacking.
9. Unlikely in this day and age. If not, then expect other copy-protection measures which you might find equally inconvenient.
10. Again, unlikely in this day and age. It's quite sad that we can't have the days of Falcon 4.0-sized manuals back - I'd pay extra just for the good documentation!