If you have to pay for users, your app sucks.

What I mean is, your revenue model should be such that:
cost/install * installs/registrations * registrations/purchases < # purchases * revenue/purchase

That's a long-winded way of saying your revenue should be greater than your costs. The problem is, the cost to acquire users has become prohibitively expensive in the last 2 years. The cost to acquire users on Facebook has multiplied by 5-8x. So unless you're selling big ticket items, it doesn't make sense. If you're selling an app subscription or in-app purchases, you've pretty much got to go with organic growth.

So, subscribe wholeheartedly to the growth-hacking model. Ensure that your product has a high viral coefficient, meaning that the app experience gets better for you the more people you refer. Provide incentives to sign people up. Get people to share, and then get them to convert.

Once you've reached a solid growth velocity (double digit MoM), and your conversion rate is high, it'll be easy to get money to pour fuel onto the fire.

I'm a big fan of Pirate Metrics (AARRR), or:

A - Acquisition
A - Activation
R- Retention
R - Referral
R - Revenue

Some people throw another A on there for Awareness. Essentially you will create a spreadsheet with every product feature as a row, and each metric as a column. You then rank each feature against each metric with a 1-5 score.

In addition, I add a separate set of columns for Risk, Effort/Cost, and Impact. Score them the same way.

If you'd like, you can add a weight to each column, based on how important it is to your business at that time. For example, if you're focusing on growth, acquisition may be more important than revenue, so you'd give Acquisition a 5 and revenue a 2. You can then do a blended average, where you multiply each column score by the weight, and sum all the terms together. This will give you an overall score by which to rank all the features.

Hope this helps!

Cross-platform frameworks are just now becoming robust and stable enough to be a real concern. The most popular frameworks include React Native, Xamarin, and Ionic. The trade-offs are typically speed of development vs. flexibility and complexity. If you use a lot of platform-specific integrations like HealthKit or Google Fit, your best bet is React Native, as it spits out real native Java or Objective-C that you can further tweak or integrate. Xamarin or Ionic basically put wrappers around C# or HTML5, so your deep integrations are limited.

As far as the architect is involved, you're looking for someone who has experience in both Objective-C and Java, as well as the cross-platform language, whether it be Javascript or C#. This is because once you've built your cross-platform app, you still may have to write native libraries to integrate to the platform-specific features like HealthKit.

I can't speak for the education industry itself. You can post listings on Angelist or StackOverflow, but also scour LinkedIn to attempt to poach people. You have to assume a good architect is already well employed and isn't looking for work, so you're going to have to go out and find them.

I've ran into this problem before, in that good architects are really hard to find. It may be easier to hire a good mid-level developer, and train them in architecture. That basically means carving out 40-50% of their time to spend on architecture and research. They will then grow into that role in 6-12 months.

Hope this helps.