-- Prototype -- I would add that you can create prototypes more simply by just using static images and adding interactive elements to them. I recently discovered MarvelApp (https://marvelapp.com) and you can create mobile + web prototypes for free with them. I would recommend hiring a designer to...
There's a lot of marketplaces where you could promote the app to avid travelers. I work mostly in the travel space, and building an audience is always the hardest part, especially since there's so much competition. You have two great options, and the first I'd say is to create a press release. ...