I'm a self-taught mobile/software/website developer with experience for over 3 years. I strive for perfection and I'm willing to help in every way I can. Currently I'm starting a company specialized in programming and robotics.
There are many ways to solve your problems. And to me the main problem in your case is money.
In my opinion, seeking for an investor nowadays is useless. The most popular way to raise some money today is crowdfunding. You can go to indiegogo.com or any similar website, present your project and the amount of money you want to raise and people will start making donations. Or you can look for a developer who's willing to go into a partnership with you.
I'll be more than happy to discuss more details with you on the phone.
Their's no trusted source for knowing how many downloads a specific app has gotten only if the developers of the app publish some numbers.
However www.xyologic.com presents the number of downloads for a wide variety of ios apps in different categories but I'm not sure about its reliability.