1) the diagram from installdr.com says my wiring for the Ignition/Accessory wire is Yellow w/Red stripe. Would it be true that ANY wire on my car (not just the wires from the head unit) that's yellow w/red stripe is an Ignition/Accessory wire? I'm having trouble getting to the wiring from my head unit to splice into the Ignition/Accessory wire, but there is an unused harness under the driver's side that includes a yellow wire w/red stripe. Can I just use that to run my amp's remote wire to (installation instructions with the amp say to run the REMOTE to ACCESSORY/IGNITION wire if using the factory head unit and there is no head unit remote wire to connect to)?

2) I bought speaker wire harnesses made by Metra/Dashworks that will connect to my factory speaker wire harness. The aftermarket harness has a black wire and a white wire. Is it safe to assume that black is negative (-) and white is positive (+) for connecting to my new aftermarket speakers?

Thanks in advance!