you;ll want to add a LOC after the amplifier. If you have a factory sub you can grab your signal there. I usually grab the rear speaker leads in the B pillar before it goes into the door, i've found that the easiest place since its already apart for running your power.
Remote can be grabbed at the Acc Cig socket in the dash.
For myself on mine, I used the interior junction block with an "add a circuit" fuse such as this:
The interior junction block is not powered key off, with this you can piggy back another circuit or grab an open space (iirc there were 1 or 2).
I went through a big rubber harness gromet down below the brake booster, a wire hanger to help feed the wire is a must.
Not all loc's are the same, I have been told some you supply power to and using the audio signal the will activate an internal remote control (this would be better than my suggestion), Im sure as with any electronics... you get what you pay for.