Find another installer. And read the sections in the FAQ about the tuner (in the Troubleshooting section) and about the ground loop (in the installation section).

Your friend is right, there are only 4 wires to deal with:

- Continuous power
- Ignition switched power
- Amp remote
- Ground.

Pretty much everything else is optional, such as the headlight sense wire and perhaps the cell phone mute wire. But they should be all pretty clearly labeled, if not at least carefully described in the manual. Of course, amplifiers always complicate an install, but if this guy is such a master installer, he should have installed hundreds of amps already.

So yeah, get a refund and run away from that installer as fast as you can. Find someone else.

Regarding the amp remote wire: Its job is to signal to the other devices when they should turn on. It does not "kickstart" anything, and therefore does not need to supply a lot of power. Your amplifiers should be connected directly to the battery (with a proper weatherproof fuse block in the engine compartment of course) and getting their power from that location, so the amp remote wire does not power them, it just signals them. So you should be able to connect a bunch of amps to that amp remote wire as long as they are connected PROPERLY.