Nah, that's just the total mess that Haru scribbled onto the page to show off what she had already come up with. Her real autograph is different. It's on the IM@S-Wiki if you want to spoil yourself. Or you can just wait a few more chapters, the real one will be revealed by the end of the volume.
It is admittedly a bit confusing. There is definitiely no page missing, I checked this against the raws. But I'm also not fully sure why it feels this weird. I also checked the raws again to make sure I didn't mistranslate anything, and there is nothing inherently wrong with the translation...
Yep. Without going into any details, there will be a lot more about this in the next chapter. This one was pretty much just a setup for what is coming in the next chapter. So look forward to what'll happen ^^
Not really sure about the game, haven't played it myself, but yes, this is generally considered a spin-off. The story is completely separate as far as I know and the only thing it has in common with the main series is the characters and the general theme. Some of those differences result in...
Yeah, pretty much. Take a look at the upload on the wiki. I think she merges the two kanji that make up her name vertically above each other. At least that's what it looks like to me.
More or less. We're not really missing a lot of character chapters; actually we're only missing two from a quick glance over the table of contents of all the remaining volumes. And both are for Kozue, who apparently hasn't had any chapters fo far. A bit surprising.
Beyond that we'll probably...
We've actually still got quite a bit to go, there are still roughly 40 chapters left to go.
It is a bit weird, but I think there is still quite a bit left for most of the characters. I think I'm about three chapters ahead with the translation, and I've also flipped some of the later pages, so I...
The chapter is Flowering Fight, which is chapter 88 (91 on MangaDex)
The opening act probably refers to the events from the Chie storyline, or chapters 16-20.
And regarding your third question... well, I don't know the answer either, sorry. That would probably require someone who is more...