My main question to you is: Do I need to ask all these entrepreneurs for a permission to write about them, or there is no problem since it would be giving them kind of a promotion and maybe new audiences?
Disclaimer: No one except an attorney can give you legal advice, and please don't take my opinion as legal advice.
If you can get someone's permission, that's always the best route to take.
My question for YOU is: What kind of value are you going to provide on this website that I couldn't get by visiting the blog or listening to the podcast of the original entrepreneur? I like Pat Flynn and I like reading his blog. Why would I read your blog about him instead of reading his own words? Just something to think about.
I'm 100% behind you on the idea of getting a project started where you can learn those skills that you mentioned. That said, it's best if you aren't spinning your wheels - it will be a lesson in futility instead.