Please rememeber that a slideshow is just one tiny piece of the teaching puzzle and SlideHero is not trying to be everything for everyone.
All those things you mention are good, and necessary (adjusted for audience age of course) and a good teacher will add all that value too and that can and should happen outside of SlideHero.
My goal is to reduce teacher load by just enough that teachers see the value in paying me $7/month :)
Yeah, I'm totally being too hard on you. Apologies if it comes off too harsh.
All the power to you & good luck with the project! Teachers deserve every help they can get.