rsgonza

Hello.This would be the first time installing a 4 channel amp using a factory h.u.Ive done some reseach and I think Im clear on a few things but would like a few ipinions please ok.
On my 99 f150 I have a kenwood h.u with an alpine 4 ch.amp and a single sub box w a 500 wat mono amp. kicker sub.infinity ref.door speakers.I love the sound .I listen to classic rock metal.classic metal preist maiden ac dc.anyway.I had just enough bass.
Now I want to use my facoty hu.(non sony) I have infinitys ref already installed.I also was thinking of going with the same 4 channel alpine amp.
For now I will hold off on a sub.
My questions are
1 is there a sub box that would fit under the pass side rear seat.(small seat) w a 10 inch.I have found sub boxes but they fit on the drivers side.
2.I walked into a local audio Place and asked them how much they would chanrge to install the amp.They mention installing a pac line convertor and then amp.will the pac work fine or should I be looking for a sound proccesor.They claim it will be fine.Im not to sure about that?
jb audio clean sweep?audiocontrol lc6? or a pac loc.
3.viper alarm vrs clifford.they look the same is this strickly preferance.I have a clifford in my 99.
Thank you all .