Have you tried the recently announced Newsfeed Ads for Messenger to drive traffic to your bot?
https://developers.facebook.com/blog/post/2016/09/12/new-mes...
https://developers.facebook.com/blog/post/2016/09/12/new-mes...
2. I'm genuinely interested to hear other success stories and learnings. Are people finding that Messaging apps are 'build it and they will come' or are there new techniques for driving usage?
I'm personally not very convinced about automated conversational interfaces, but Messenger does provide a great opportunity (1bn users) and platform (ios/android/web) to create and grow new kinds of applications with very little effort, if only we can figure out how to get people using it :)
The top comment on this post is the same topic, worth checking out. Thanks for the bookmark.