1.) I divide up the chapters during the writing/storyboarding - which for me is pretty much the same thing. I have an outline of the major events/plotpoints/scenes, but I don't split it into defined chapters until I sit down to actually write/storyboard that part. For example; my first chapter was actually TWO chapters to begin with, and I had started drawing the finished pages before I realised that they would work better as a single chapter. Happily, combining them didn't actually mean changing very much. But yes, usually, I do my division when I start storyboards/dialogue writing.
2.) I do NOT have a set number of pages, but I do try to not have chapters that are too short. On the one hand, I don't want chapters that are too short - it feels weird - but on the other hand, I don't want to pad a chapter out with extra pages just for length; my comic is slow-paced enough already. Thus far, Grassblades-chapters vary between 17-33 pages. I try to break on natural points of the story - when characters physically leave one place and move to another, or when they fall asleep, or when they've finished a particular conversation, or something like that; they feel like good ways of wrapping up.
3.) I haven't done any cliffhangers - YET. I might later on, for drama. But I don't want to overuse them, because then they're actually LESS dramatic; it's a matter of impact. I don't do recaps - they feel like a stylistic artifact left over from monthly superhero comics, which need recaps to get new readers up to speed for jumping-on points, or to remind old readers what they read last month; I don't feel the same need for it, as there will be at most one week between chapters on my part.
4.) I do individual covers for each chapter as separate images; I like the way it looks, even if composition of covers is a lot trickier than it seems. I HAVE done it the other way for other comics - with the title as part of a page - but I don't think I'll be doing it with Grassblades.