Yep thats it for wiring, and yep red is positive.
The copper-ish is wire indeed positive (although it truly doesn't matter, the speaker will not care either way since in reality sound is just AC power)
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The only reason + and - for speakers is there is to have the sound correctly in-phase...
Try this for a neat little trick:
Setup the 2 factory speakers fairly close together, and connect them normally
If it has one, make sure the left/right balance knob on the stereo is exactly centered
Play something mono (like an AM station)
Start right near the stereo (exactly centered between the speakers), and slowly back away from it...(this part is simply for comparison, it'll sound just as you expect)
now re-connect +/- backwards on only one speaker.
Again start right near the stereo (again exactly centered between the speakers), and slowly back away from it... You should get some weird sound-cancellation effects, even spots where you hear -nothing- no matter how loud its turned up!
Lots of fun to play around with that
I one time had a 2-speaker mono amp setup at the back of the yard, and purposely connected one speaker backwards, walking around and turning my head just right could make the sound appear come from various directions....and I mean to the point of being so convincing that if you were blindfolded you wouldn't know where the sound was actually coming from. There was one time I got things setup just right and found the exact right spot and it sounded like the music was coming from inside my head