Hi, this is a common query by NRI students and parents when it comes to NEET. In engineering its much more understood and common. 

But, lets come to the concerns here. 

1. Is he restricted to 15% NRI Quota only. Yes, he is eligible for state 15% NRI quota in NEET. This will be based on the domicile. This NRI quota is valid only in your home state only. 

2. Get good NEET Rank - Will he be getting admission at higher fee or nominal fee - It will depend on merit. If the NEET score is good and he manage to get into the Govt. Medical Colleges then surely fee will be lesser but little higher than the regular indian students. In case of private medical colleges which also accept NEET score, here fee will be exorbitant.

Hope your questions is answered!