I got a 94 Dodge Spirit that i drove for 7 years. It blow a head gasket at 320k miles. Besides the transmission going out twice, that was the only real problem out of the motor.
Yes u need a line driver. It will cut out any noise your having and give u more head room on ur amps. You can get a Phoenix Gold 8v on ebay for $35. And it will be alot louder.
I use refill. I think people get the wrong impression about it or heard some not properly installed. Its like you hear them but you cant tell the sound is coming from behind you. It just enhances you front stage.