I'll be glad to answer questions regarding development, audience and similar aspects, but I'll do that tomorrow as it's just past midnight in Europe/UK (where we are based). Also feel free to ask about our monitoring service, I'm sure my colleagues will chime in where my knowledge ends.
Overall it's nice to have the same tools and codebase for both platforms, just adapting the app for notably different use cases.
This decision was made easier due to the fact that both platforms can run the same code, so most of the API interaction and view rendering code will be reused. It was mostly a greenfield project, because even though we leveraged the knowledge from our alerts iOS app, we took the opportunity of writing everything in Swift, which functional expressiveness makes it slightly more useful when it comes to dealing with APIs.
For apps not tied to an existing web property (I'm planning to do some games on my own, for example), you need an effective marketing channel, even if it's just word of mouth. No one is going to just come up with some search terms and find your app.