How to publish an iOS application in the App Store?

Question

iOS

I started to study the issue of laying out the application in my company and there are questions, I hope you can answer.
1. We need a paid application, do we understand correctly that we need to register a company / legal entity account, a developer account is not suitable? Is it possible to register a company/legal entity account if we have an individual entrepreneur? To register a company account, we still need to obtain a certificate, i.e. issue "DUNS number"?
2. I signed up, paid and I need to understand what I need to send the application to the AppStore (icons of different sizes, screenshots, and what else?). Is there an exhaustive list of these requirements, where it can be viewed on the AppStore website.
3. I paid and sent and everything is OK, then I need to sell the application to a large customer, for example, a university that needs to install this application on several devices. What scheme is usually used in this case?
- the author buys promo codes from Apple and gives them to the university, and the latter, in turn, to the students
- the university itself buys promo codes in the application and gives them to students
. Is there information about app monetization somewhere on the site?
3.1. What happens if once the university purchased access to the application for 20 devices, 20 students unlearned. How to make it so that the university should again be able to buy access for the next 20 students.
- time limit for using the promo code?
What other tools are there?