Our artist isn't a fan of NTR, so we wont have many more, if any.
I won't go into the specifics right now, but we're working on a total re-vamp of the combat to make it closer to an RPG.
I cut the quote to avoid a full wall of text, but I'll try to address most of what you brought up in this post.
There will be a little scene with Nurse Kate in the next update that will hint at her back story, but I have things planned for her backstory I haven't even talked to G-zone about. It's actually phenomenal working for him, because he gives me a ton of freedom when it comes to the writing. This scene won't be on the main path, so you'll need to do a bit of off-roading to find it. There was an easter egg in the last update, and to my knowledge nobody has found it yet. That's going to be more and more common as we move forward, and as we roll out the mechanics we want to implement those easter eggs will have impacts on the game as well.
When G-zone started this he was definitely inspired by Summertime Saga. Now as the project has matured a little bit we're going to try to develop a more distinct voice in the industry, hence why we're going to be adding more RPG elements, refining our combat system, and aiming to have a much more defined structure to the game. The "open world" with linear quests structure wouldn't really work for a game based on an episodic TV show.
At the moment I have plans for Dani in the writing, but she's definitely on the back burner. The way we're structuring things right now is an attempt to capture the feeling of a Danny Phantom episode. So one human girl, one ghost girl, and some background enemies/npcs per episode. I've mentioned it a few times now, but next episode is going to be focused on Sam, then our current plan is to do a Maddie episode after her. We'll probably end up letting the patrons vote on that once we're done with this episode, though.