1) Is this a cloud/online product, or does it require desktop installation?
2) I see it mentioning the a Preview is available, but I can seem to find it on my Office 365 apps panel (I'm a Business Premium account/user).
1) It's both cloud based and has a desktop app. I believe the demo screenshots I saw were all in the browser though.
2) There was a mention that it wasn't available immediately but should start showing up somewhere in the dashboard around 1:30 EST. You might have to find it somewhere deep in the settings if I remember what someone else showed me. I.e. it's not in the main app grid by default and has to be enabled.