2- That would require lots of animation and the team is not a fan of making them. But i understand what you're saying about the shoes, i'd actually like t see sims, at least, have a "touching the foot" animation and then the shoes disappear, something like what they use on GTA V RP. For the jacket issue maybe that's happening because of the cold temperature, that can kill sims.
3- Well you can lock the door, but as you said you don't want to be doing it everytime, the easiest thing to do is let the door locked for everyone but the couple. And if there's something there that the whole family needs you should place it somewhere.
4- Yeah, i agree. I even made a topic suggesting something less intrusive a while ago (is it similar to what we have in paralives??):
Ideas for less loading screens | EA Forums - 11229069