I'm good with the character split. But I do remember talking about writing Keiko out. Are you still interested in doing so? 

I personally think the first case should start off just Yusuke and Botan. As the case progresses I wouldn't mind Kuwabara finding out what's going on, or just even stumbling into it. Which would be interesting if (like the anime) the two really weren't friends, but rivals, and working together they become friends. I don't, at this moment, see Keiko becoming involved if we want to stick with the idea that they've grown apart since middle school.

With the time frame, do we want to do the start of the school year, middle, or getting close to the end? I personally think somewhere in the middle/winter months, would be the best place to start. It gives Yusuke some breaks that he had investigate during, instead of skipping school or just doing it on weekends.