I'll start by saying thank you for dropping by!

I really appreciate that people are paying attention to this~. Especially considering it's already begun moving past the stage of just being an idea and actually has an existing one-page prologue. So it's awesome to have support.
And, legit, after seeing all your characters, I got this really crazy idea that we should do something one day where they get to meet. BRAIN. Y U NO NORMAL. Ah well. So, without further ado, I shall respond to your comments by character, just as you made the comments by character!
Fuyu: I'm glad you like her~. I think in my Notebook of Every Detail Imaginable, I had her visual labeled as only a couple points behind her vocal, but I always planned on her being mostly Vocal.
Enra: Thanks, I'm glad you like Enra, since she's one of my personal favorites as well...I did get the feeling when reading Setsuna's bio that the two would be somewhat similar in personality.
Also, believe it or not, there's a Cinderella Girl (I forget her name) who's even bigger than Enra. I actually plan on making a communication between her and the producer where it becomes a topic of conversation. Because fanservice. Byakura: Shy girls are adorable, let's get that out of the way first. But yeah, I liked the idea of having at least one girl with low self-esteem so you can follow her journey to self-confidence, very much like Yukiho. Because Yukiho is cute.
Kenchi: I'm gonna be honest, he's one of my personal favorites. Since he and the producer are the only guys in the group, they end up kinda becoming bros. Of course, the producer gets so used to working with girls that he sometimes forgets he can treat Kenchi like a man, which makes for some awkward conversations. It doesn't help that Kenchi tends to use "watashi" and "anata" occasionally just because he's used to having to speak somewhat formally.
Soumin: I kinda feel like out of all the K-Pop I've heard (which really isn't much, like you), Soumin's image song would be something like "Bbribbom Bberibbom" or "Too Late" by Co-Ed School. But aside from that, I'm glad you find her cute. :3
Aime: Aime and Jun could have an all-night anime sleepover. Haha, not really. But yes really, at the same time. But not. ...I don't know.
Your style is so incredibly cute, though. I envy that. I can only draw certain kinds of cute characters. Yours are almost chibi-ish, and incredibly adorable. Uane: Quite possibly. It seems like they have the same seriousness when it comes to singing.
Also, I wanted to mention that I've noticed that these characters we've introduced are actually similar, but I can assure you that I invented this group looong before I ever even knew these forums existed. Just thought I'd say something in case you had some sort of suspicion that I'd copied you...? I don't know, just making sure. Your characters are all very original too, it's not often you see a girl with a "cursed" singing voice or a half-Brazilian orphan or a rock-star who gets sucked into being a pop idol. Koko: Every idol project needs a token loli! But seriously, I'm glad you like Koko so much~! I feel like her sketch came out a little derpy, but still, it always makes me so happy to hear people say they like my characters. You're filling my heart with warm, fuzzy feels. Also, I can see Koko and Hinata getting along well if they met. :3
Mariko: For the record, Smile Spiral is an excellent song. But yes! I have yet to get fully immersed in the world of Hyperdimension Neptunia, but I like what I've seen so far and plan to get my hands on a game as soon as possible.
I really want that one with the iDOLM@STER spoof character. Chiharu: Chiharu would actually probably love Nagisa, for that exact reason. Haha, I'm glad you find her interesting. Frankly, so do I.
Benima: Kotori's voice is angelic. I cannot stress this enough. She has my third favorite im@s voice (after Makoto and Chihaya).
Choosing her to produce Project Fairy in your idea was a fantastic idea. I would love to hear them perform some of her songs like Hikari or Sora. Ruka: Ehehe~, thanks!

Ruka and Emi would probably be friendly if they met. They could make up cute nicknames for each other! XD But that's actually a pretty good plot point. Maybe the reason why Ruka's mother never got very popular was because everyone liked Mai so much? IDEAS.
Everyone keeps saying that. It'd probably be hysterical if I were more involved in the Pokémon fandom.Neku: Koneko sounds cute. I'd like to see you draw her one day. I didn't want to make Neku all about "OMG I SAY MEOW CONSTANTLY AND I'M JUST LIKE A REAL CAT AND I WEAR CAT COSPLAYS AHAHA~", but rather, closer to an animal lover with a certain affinity for cats? That doesn't stop her from having a cat-like hairstyle and ending sentences with "nyan". Because what's a cat-girl without "nyan"?
Natsuki: I'm actually REALLY happy you think so, because I like Natsuki, but I was really worried peole would be like "RAURGH YOU'RE MESSING WITH CANON DIE". I avoided canon as much as possible. I TRIED.
So, seriously, thanks a bunch!

Holy crap, she looks like she could be their child. 
Yori: I'm reeaaaally trying to avoid the Mary-Sue aspect of moderate self-insertations by having Yori be not particularly attractive but not ugly, and by making her dance stat quite low. Also, she tends to butt heads with the Producer when he tries to encourage her to get better. Even her vocals, which are the only reason she's even there, aren't as polished as some of the others. So, she's not perfect. I hope. I'm trying to make her at least a bit likeable.
But yes. If they cared, she and Hotaru could be interesting rivals. Even with the fact that neither of them care, it could somehow spark a rivalry. An "I'm better at doing nothing than you" kind of rivalry? No? Alright.
Nami and Natsu: Somehow I ended up with three sets of twins anyways (Fuyu and Yousuke, Kenchi and Kyoko, and Nami and Natsu) so whatever stereotypes I was trying to avoid with twins is probably gone now. Ah, well. I see why you would avoid it.
Tamaki and Nami could get together and squeal over cute boys together.
Just like normal American teenagers. WOOHOO.
Aaand that was really long!

YAY.
So, yeah, I see why you'd go towards making balanced stats. Honestly, I think at the beginning I meant for it to be a balanced group, but somehow everything got muddled. There's still a range (Guru, Benima, Natsu and Neku are dance-focused, and Enra, Natsuki and Nami are visual), but most of the focus definitely ended up on vocal. Maybe I'll switch Fuyu from vocal to visual, and theoretically Kenchi could lean towards any of the three. The rest are kinda-sorta-stuck-ish.
Aaaaaanyhow, I'll wrap up this super-long reply by saying...thank you!

I appreciated the feedback~. I'm glad you seem to like the sketches!
But for the record, yours are way cuter~.