well the alpine may be 80 amps plus what ever the rockford is so your well over 100 for sure. i would guess around 120 or so amps.
that does not really help me on the preouts man, a simple yes it has three sets of outs or yes i ran three sets of rca's to my amps would of been better. or maybe a yes the front outs from my hu go to the 4ch amp and the rear output is split to go to the 4ch and my sub amp would help too.
how many sets of rca's are ran from the hu to your trunk?
can you control the sub amp with the subwoofer control on your hu?