Assume nothing!!!! Ask them and get permission in writing from someone that has the authority to give you permission. If they refuse, change your name. I've had experience with larger companies sending threatening legal letters, it's not fun and it's a waste of time.

I think you're looking at the low hanging fruit rather than digging for the gold that is surely inside these goldmine companies... What I recommend is to advise all of these startups is to master internet marketing. It's the one skill set that once mastered, can and should give rise to new business strategies that can achieve that which you really want, which is an exit at 10x - 100x whatever their current valuation is... Literally ask them and their teams to spend 4 hours a day minimum learning about internet marketing, starting with the fundamentals, the pirate metrics... AARRR - google it if you don't what these are.... Have all your startups declare these metrics, then have them focus on ONE of these metrics, set a goal that is achievable but shows real progress. Give them a goal for every quarter... And don't worry about anything other than these startups meeting these pass/fail goals

You can compete against any competitor if you grind 120% every day, devote 25% of every day to studying to internet marketing. Those who master internet marketing, are dominating almost every verticle.

Metrics driven, results oriented.

Think of yourself as a content marketer first, which is effectively what you're doing, then check out convertKit, which is specifically for bloggers but works great for your situation too.

yes, absolutely

This is my favourite topic, this is all about productivity hacks and tools. Read Brian Tracey's Master Your Time book, then start checking out Productivity Management tools like Pomodoro and DaPulse and more...

Leverage pre-existing communites aka similar sites to yours - guest blogging is your friend here. Use the alexa traffic rank chrome extension to see how much traffic any similar site to yours has. Go to Mixergy and listen to every interview on guest blogging.

If you're hoping for a best time and day to sell your app then I think you're really going to struggle... What you need is a proven strategy that will create predictable results. Research the top 50 most successful app launches and you will find a pattern, I guarantee it. Distill this pattern into a formula, and then execute.

That's a bad gamble imo. What exactly do you mean with validated???? Validated to me usually means pre-sales. Literally, their money in your bank account before you risk any of your hard earned money and precious time, then there is much less risk to you and the fact they are prepared to kickstart your development is a strong validation signal...