There's a simple solution to all your questions. How is the worth of most things in this country determined? The answer to that is called free market. The NCAA does not have to determine the worth of any athlete, let the free market decide that. The biggest issue isn't that athletes aren't getting paid it's that athletes are being RESTRICTED from being paid. By that I mean if a booster wants to give an athlete $50,000 to come to their school, Why is that a problem? If Ohio State wants to pay a player on top of the free education, room and board, etc that they offer, why is that a problem?
I'll use an analogy. Let's say there's a genius young scientist in high school. They do a project and it's really grounbreaking. And for that effort Harvard tells them hey, if you come to our school we'll waive all your costs and pay you $50,000 a year to your research efforts/stipend. But then Stanford steps in and says we'll match Harvard's offer but instead of $50,000 we'll give you $75,000 and a car. And on top of that Google steps in and offers them an additional $50,000 for them to go to Stanford because they want this scholar in the Bay Area. Would anyone have a problem with this?
Why is that situation any different than a premier athlete?
Here's the simple solution to this. You do not have to in state a rule that makes Universities have to pay players. All you have to do is remove the rules the restrict the from being paid. Let the free market decide.