Meteor App with Wordpress Frontend

This might be a stupid question but hey, here goes…

I am in the process of building an app with Meteor (and still have a long way to go) however, it is my first app and I have never actually deployed an app into production. I was wondering how I would be able to have a Wordpress site set up on my main domain (www.myapp.com), and then when a user logs in (to the app, not WP), they are taken to a sub domain (app.mydomain.com).

Does anyone have any recommendations on how to set this up?
Would I host the app and WP at the same location? Say DigitalOcean/Heroku/Galaxy?

Thanks