1) I am aware of this issue, and while adding a map that keeps track of the people is not something that is on the scope of what I can do, newer chapters will start to add text telling you where you can find some characters depending on the time of the day (the latest chapter that at the moment is on Patreon has this). Also, I'm working on making some beds available for the player across the different maps, because having to go back and forth so much to change the day can be annoying.
2) No. There are tons of games that focus on skinny and muscled characters, but not that many where you can have many options of chubby characters. If I had the time, I'd probably add more types of chubs, to make the game feel more varied, but keep it within my vision.
3) I am a one person team, so there is only so much I can do by myself. This means any ideas I had for side quests are things I see if I can add after I finish making the main story of the game.
On the other recommendations:
1) Yes, the errand system ended up not being as fun as I expected, so lowering the numbers might be a good idea.
2) This one is trickier to pull off. But the idea is that 5 stars interactions will be doable over and over again.
3) Characters you meet during errands will also be available to meet, just later in the game.
4 & 5) Combat balance is the weakest part of the game, because I'm mainly focused on the other aspects of it. As I said, I'm just one person and I do this during my free time, so it's unavoidable that some parts of the game will suffer for it.