What software (API, plugin, etc.) should I use for my website to assist in complying with COPPA policies?

Non-disclosure agreements are very common. Know that a non-disclosure agreement goes both ways as well. A contract agreement should also protects you from the other party disclosing any trade secrets or know-hows that they may learn from working with you.

I'll keep try to keep this answer brief, but there are several factors and nuances that can be discussed in more depth. Where you decide to incorporate partly depends on what your future goals are with your company. Companies that plan to seek venture capital or go public typically choose Delaware as the state of incorporation, and usually choose a C-Corp. Delaware has a very well developed body of law surrounding corporate governance and that provides comfort and more certainty to future VC investors. If you're not planning to seek VC money any time soon, an LLC is a smart decision because of the tax benefits it can provide to you as the owner. It sounds like you want to grow your company on your own without outside financing. If that's the case, I would recommend forming your LLC in California. Regarding California vs. Delaware, one benefit to forming your LLC in California is that you can avoid paying a registered agent fee which can cost anywhere from $100-200 a year. If you plan to seek venture capital down the road, you can reincorporate in Delaware.

I do not believe you should incorporate your company yet as there is a chance you will scrap the idea or iterate on the assumptions after analysis. I suggest you run your initial testing on a very minimal MVP to see if there is interest. I would go further in saying that you should not even allow people to pay only have them click on the payment option because at that point you know that it would be a conversion. The ONLY thing you are proving with an MVP is validation of an idea. Only make the mousetrap front end and see if you can drive users to where you want and stop. Even if you frustrate some people, it was worth it as you now know for sure people will buy or do what it is you wanted. Schedule a call with me to find out more. God knows I have done this enough times. Good luck Josh

On paper you have the advantage but after several startups control resides in he who knows how to execute the vision of the company.

I developed and published mobile apps as an individual for several years, and only formed a corporation later as things grew and it made sense. As far as Apple's App Store and Google Play are concerned, you can register as an individual developer without having a corporation. I'd be happy to help further over a call if you have any additional questions. Best of luck with your mobile app!