Bhai if ur painter has to spray clear coat over white to give it shine, then he did a very bad job originally. spraying clear coat over existing white will make it glossy but when u will see in detail, there will be thousands of pin holes...its a bad idea
Paint with already hardnener in it will.not allow lacquer to settle properly, thats why lacquer is mixed with hardner and used over a base coat without harderner. I can tell u painter who will match the factory color..and quality will be pretty close to perfect. When u will argue on pin holes, he will say ...sir g abhi compound kernay dein phr dekhain
ap close ups dekhain paint ki and if u got whole car painted?..send pics when car is parked under tube lights or cfl bulbs