Does it really show what subreddits people are posting their videos on? Useful for finding appropriate subreddits in your niche. Is that the free version?

Yup it shows. This one tip is probably responsible for over 30% of my subscribers. And as far as I know, I haven't paid a cent :)
TubeBuddy has been my YouTube buddy ever since I discovered it. Even vidIQ loses out in terms of analytic features.