Hi there!
I've been following this topic since it was done, but never took the time to answer this and wish you good luck, sorry ^^" Better late than never?
1. First impression in general? (On story, game type etc.?)
It seems that this story has a high comical-potential due to the fact that the characters are... hum, bright with colours? They all seem really different and sweet in some way. The interactions between them already sound good somehow!
Besides I quite like the fact that we can get to choose the gender of the character and that it means living the stroy on one side (Ryuuga's) or the other (Travis'). It allows the MCs to have real personnalities rather than just being the fe/male version of the same character. Good choice!

The art also looks really good (as always we will only be sure when we see the complete game), but it really looks good!
I'm usually not that much into Slice-Of-Life (because it can easily get boring, exactly like real life) or into simulations (because I suck), however I will definitely follow your game closely because it has so much potential!
2. Any characters that you already interested in? Or characters you already think of as boring?
I'm more interested in the interactions between the MC and the characters than the characters themselve but...
These duo seem interesting:
Ryuuga/Cyan
Travis/Marianne
Ryuuga/Travis (and Travis/Ryuuga of course)
Those ones seem less interesting to me:
Travis/Tracey
Ryuuga/Marianne
But I'm just saying this based on a short description and on my own imagination, so I may be wrong. It's just that some duo seem more dynamics than others ^^
And rest assured that none of your characters seem boring
3. Which character will you probably play as first?
Probably Travis, not because I'm a girl (I am though) but because her personnality seem funnier to play X)
4. The café management will influence the CGs you get, but not the endings (except for the bad ending). Is it fine like that or would you prefer the café management influencing the endings more?
It's fine! Perfect! So that we can suck at the café Management and still enjoy the game
If it makes sense that sucking at the café Management can still allow someone to get a good ending, I'm okay with it.
If it'd seem strange that you can't manage the store and can still get a happy ending, then I'm against.
Everything depends on if it makes sense to you ^^ You're the mastermind of this game afterall
5. Was the information on which character is dateable too confusing? XD' (I didn't know what to use other than the icons XD')
I had to read twice before understandign but that's probbaly just me
It was easy to understand

And it's nice to see all kind of romance ^^
6. Other critique / suggestions / questions? Let me know >w<
I've seen the little text about Cyan's age.
I honestly don't really mind if he's young (since you've said that there would be no questionable scenes). he just doesn't really look 15, but, hey, everyone ages differently ^^
I wish you all the best for this game!! It looks really good so far!

Good luck!!!!! (۶•̀ᴗ•́)۶