You probably don't need a PR.
It appears that the net effect of selling more seats for less money is almost always positive, so it's best to set the prices so that you don't sell out a category, but you get close enough.
Merchandise boost from homegrown and own nation's players can be fairly big, especially in higher divisions.
In any case, he did respond to the question somewhere in there: overextension was created to prevent people to just buy high salary players and winning trophies that way. Now you either have to have a positive balance or cover the shortfall with the salary increases you got from players you trained or you are taxed. I have a salary exemption from training of over 220k on one team and 170k on the other, this means I won't have to pay the tax even if I have a -150k balance. The tax simply accelerates the rate at which you lose money, if you are in the red.