How is it possible to submit an app to the AppStore which is not for general use? For instance I might want to do an invite-only free trial before making the app generally available for a fee.
Or I might want to be able to give free copies to specific people for promotion. Are these kind of things possible?
Create an ad-hoc distribution.
It’s all detailed very well in the iOS developer center, it’s what you need to use for beta testing, etc.