Still need answers ? I want to share my opinion too
1) We all know 3D modelling isn't that easy and requires a lot of time. So having characters almost indentical is somehow logical for all of us, who are more into developping than "artist-ing". But tbh, as a player, as long as they're just not the basic models with 0 modifications, it's ok. I mean, if it's your characters, then you should at least add your own little touch to make them like you want.
2) VN is a great style, and more than that it's the easiest way to use Ren'Py, which tbh is the easiest game making software. BUT, if you take a look at how are designed the more popular games (using Ren'Py, I'm not really playing other engines, because you know, free hand..), well, you will see that they're well developped VN with a lot of emotions, not a boring context/story, a variety of choices that all have different impacts on the story AND a hud with data about the girls present in-game. Most of them also have a way to move around by yourself instead of only following a said story.
SO I would assume that having a great STORY game, with a bit of GAMEPLAY is what comes best.
3) I don't know about CoC, but if it's text only (like back in the Atari computers day), then nope. I mean, I'm not reading 50 shades of grey, right ? But, if by text-based, you mean a story which is really long-written with images that come up with, like in "A Wife And A Mother", then it is a Yes ! Those are so rare, but it's understandable. I mean, who really wants to just repeatedly click to go through a story ? If you add the elements that will make your story reliable, then SUCCESS ! Add emotions, add visuals, add deep choices, dilemmas, morality, ethic. Make it look like a fucking movie script ! Make the characters realistic, with a strong story, and people will play that game.
BUT, combining a RPG/Simulator game with a Huge storyline behind could not be the best option. Who wants to roam around a game during hours of history for almost nothing ? What would be the point of having control, if nothing happens ? That's where the breakpoint is, where you need to choose what you want that game to be. Either a narrative or an interactive one.
I studied Game Design in a private Uni in France, and the main thing that I was taught was : There are always 4 elements in a game. Story - Gameplay - Esthetism - Technology
Story : Well, can't be more self-explanatory. What you want to tell basically, what is gonna be the core of your game.
Gameplay : Without a decent gameplay, players are more likely to get bored/frustrated by how they can play your game.
Esthetism : Esthetism doesn't mean high quality graphics. It means a logical visual universe. E.G. Minecraft is more esthetic than the new 007 games. Why ? Because Minecraft creates an illusion of beauty with how it works. The movie-based games just want to be imitations of movies, which never works if it's copy/pasted, even though movies were decent.
Technology : That's how your game is gonna work. E.G. Does it require a controller ? Is it on console ? What engine does it use ? etc...
Once you get all of this right, then, you have a decent/valid game. But if at some point you forget one of those 4 rules, you'll end up doing an incomplete work. To give an example, that's exactly why they added a Storyline into Racing/FIFA games. To complete what they built over than just publishing the same video game every year. What makes the difference is HOW YOU make the difference !