1) As much as not having to manually dial would be a nice quality of life change I do think it would take away from some of the charm. Maybe after earning a certain number of wins the phone can be replaced with a numberpad phone instead? Just a thought.
2) Again I think it adds to the charm. It slows you down sure but for me that's the feel the game is giving. The steps of closeing the shutter, picking up the phone and then manually dialing the DDD all feel like a way to pace the game out. I do see how it gets tedious after doing it 100 times however. (I myself have put a good amount of time into the game)
3) Would be a cool change I agree.
4) Yeah I also think this'll be pretty cool. Make the noraml difficulty super hard and much more subtle changes. (as a seperate mode or difficulty slider)
5) Think you've just been lucky/unlucky. I've had loads of wrong names and numbers. Heck some rounds I don't get a single appearence difference and all just document based changes. "like giving the wrong job, the wrong apartment number/floor, etc" They can have the wrong reason where it says "My apartment is floor 3 room 2". Sometimes that can say the wrong place. I agree on the apartment number and job though. I always check these just encase but they're always right.
6) Oh interesting! I've never noticed any myself (Native english speaker) but i'm just likely too ignorant to pay attention.
One quality of life change i'd like to personally see is the ability to cross people off the list. If I let someone in I think it'd be cool if I could open the list back up and just cross that person off. However I do see why maybe this won't be a good idea because at the momen the lack of ability to do this does add to having to memorize who you have and haven't let in yet. It also gives you an exucse to call their apartment to check if you already let them in. So this might not be a great quality of life change.
Something that could also be cool is the ability to earn money? Then spend that money ON quality of life upgrades. So like mentioned before about a numpad phone or like i just said with crossing people off. The ability to buy a numpad phone with points earned from playing or a pen would be kind of cool. Would make the game feel like there is more of an "end goal" even if it's to just unlock things.