1. it has not been proven that it produces better sound fcaing backwards, it is all personal preference and the make of the car. SOme cars with the subs firing upwards produces louder sound. The hatch revererates the sound waves from the subs, but facing thme back wards dows not sound amazingly better. In fact most people without an acoustical ear cannot hear the difference.
And 2. sealed or ported is once again the listeners preference. The sub will produce more output with less power in a ported box then sealed, but will lose some of the sound quality that it has. But because it is an re audio woofer putting it in a ported box will not hurt the sound much at all. Upgrading to a ported box from a selaed box will increase the output of the sub, which is what he is looking to do.