Don't worry, I'll let you know if we ever hit that point!
I'll try and tackle these as you've broken them up as I feel that might help keep myself organized.
Identifying with dad wasn't really an intention. He was there to contrast Dave's fairly muted persona amidst his sadness and give a Dave-biased look on how his father was/acted. He's more hyper in the dream sequences compared to the flashback on Day 15 (outside of the Day 11 dream) because Dave is hyperfocused on 'positive' things when he's thinking of his dad. Essentially, it's a symptom of repressed trauma if a gross oversimplification of what's going on. It's why the dream sequences aren't meant to be indicative of how good a father David was to Dave, because they're inherently tainted with narrator bias.
Day 10 - I feel I answered why this feels off above. This isn't his dad. This wouldn't be how he responded because this is Dave just using his dad as a crutch visually to process his stress. We're introduced to dad as needed Dave clues in that it's a dream by asking the name but takes more comfort in the lie and what he wants to hear than what would actually be sound advice. After all, this is all in his head.
Day 11 - It was meant to be the first hint towards a strained marriage, yes. Perhaps I was playing it a little too subtle with the subtext of them not arguing in front of Dave but Dave still being somewhat aware that something was amiss. Very few people have picked up on what that scene was about so I might need to make it a little more explicit so it makes sense for a later scene.
Day 12 (1) - The suggestion is sound outside the the friendship group functionally splitting apart after the month, so thinking about them together minus him wouldn't resonate correctly with how he's feeling. Something closer would be having them all over and then in a flash they're all gone. Even then it's a little off because he's equating: people he loves going away = friends going away = isolation. Because dad's already gone, his friends are mimicking that gap by also being missing here. Mom's already out of the picture but we'll get to her later.
Day 13 - Ah, not a dream this one. This one he is just consciously thinking back to a memory he had. Again probably a case of me trying to be too clever and subtle but the tonal change is because he's still awake versus in REM sleep. But it's the fault in the memory that leads him back to what happens immediately after with the river.
Day 14 (1) - That line is important but just... not right now. I'm a big fan of narrative echoes, and when you start messing with the topic of morphic resonance the 'when' and the 'how' of that line coming up makes it a little harder to judge if it the payoff is working.
Day 14 (2) - So the dislike of the living room is due to that being the room his world broke down. Might have been to heavy-handed with Dave's descriptions but I'll review it. The color thing is because a symptom of severe emotional trauma is partial colorblindness. Coupled with what colorblindness hyenas already have exhibited to have IRL I figured this was a good symptom to apply. The lack of knowing how his dad died is because of him actually just not knowing the circumstances.
15 - Why show dad here? I'm not opposed to the idea on principle but I don't know exactly what that'd be adding given Dave's focus is primarily on his route partner instead.
The two scenes: It's funny that you mention this, as I have a draft of something similar to this but it's not a dream. Something for later when Dave decides to embody the man his father was/wanted him to become once Dave's arc is closer to being done development-wise. We open the game up on Dave being depressed over his father's death, so looking fondly on him being a cool hero doesn't work if the hero is dead. Scene two would be something to lead into the story on Day 14 about hearing the news if only visually being able to capture the red/blue lighting on the scene. It might be a little heavy handed though, but I can draft something up and see how it reads.
Something I worry about constantly and won't stop worrying about until this game is done, is that my writing quality as far as set ups and pay-offs can't be accurately judged until said pay-offs happen. Narrative echoes that I've put in now don't seem as such because nothing's echoing back just yet. Another case of this would be the recurring lines of "Just give up, Dave. Let whatever happens, happen." Dave got these words from somewhere, but we don't know specifically where yet as the story isn't that far along.